Wrestling in its simplest form could be likened to a conveyor belt. Superstars are on the belt for some time before they are then moved on and replaced by someone new. No one is irreplaceable in wrestling and in this era there are hundreds of other superstars waiting to take a spot if someone decides to walk away. Of course, walking away isn't the only way out of a WWE contract There are a number of other issues like injuries and lack of creative control that end up annoying some superstars so much that they decide to leave. In these cases the company is the reason that the Superstars have been forced out. Sometimes this is intentional, sometimes it is just bad timing.

There are more superstars in WWE right now than ever before, so it is much harder to make sure every star is happy with their role in the show. This means that there will always be reports about backstage heat because someone will always have a problem with their position in the company. Retirement is also a huge thing that will affect WWE over the next 12 months with many big stars looking at their final year in the company next year.

The following list looks at just eight WWE stars who will be forced out of WWE in the coming years because of these kinds of problems as well as seven who are the most likely to quit.

15 15. Forced: Brock Lesnar

Brock Lesnar is the current Universal Champion and has held that title ever since WrestleMania 33 back in April. It has become well-known over the past few months that Brock's contract with WWE comes to an end in just four months time. There haven't been any reports about The Beast wanting to sign a new one.

There is a plan for Brock to drop the title at WrestleMania. Then he can walk away from the company and perhaps take a lengthy leave of absence or decide if he ever wants to come back at all. Brock's past five years in WWE have been the best of his career but the creative team are running out of ideas of him and as a part-time star it seems that it may be time for him to step aside.

14 14. Quit: Shinsuke Nakamura

Shinsuke Nakamura was a well-known name all over the world when he joined WWE a few years ago. While he was used to the best of his ability on the NXT brand, he has been somewhat underwhelming throughout 2017 on the main roster.

Other superstars have commented on just how bad Nakamura's run on SmackDown has been over the past few months as WWE have seemingly done everything they can to bury the former NJPW star. It is starting to look as though he will never become World Champion. Nakamura is the only man who was defeated clean by Jinder Mahal while he was Champion, and it was in the main event of SummerSlam. How much longer can Nakamura continue to put up with this before he realizes that he would be treated much better elsewhere?

13 13. Forced: Dolph Ziggler

Dolph Ziggler has been the subject of a number of rumours regarding his WWE departure over the past year as his contract with the company is set to come to an end in the next 12 months.

Ziggler walked away as part of a storyline on SmackDown Live the week before Christmas. There is now a United States Championship tournament to crown a new Champion after he seemingly vacated the title he had won just days before. Ziggler hasn't been used effectively in WWE for a while now and his new gimmick hasn't gotten over with the WWE Universe very well either. It seems that the creative team have just run out of ideas for Dolph which is just as well since his contract is coming to an end anyway. As of yet he has shown no desire to sign a new one.

12 12. Quit: Neville

Neville hasn't been seen in WWE since the week after he was forced to drop his Cruiserweight Championship to Enzo Amore back at No Mercy. There have been a number of reports surrounding Neville that suggest the former NXT Champion doesn't want to come back to WWE. Apparently he isn't happy about the way he was used in the company throughout the year.

It was reported that Neville had been unhappy for a while. Even though WWE has held talks with him to find a way to bring him back recently, these haven't been going too well. The fact that Hideo Itami has recently begun using the Rings of Saturn finisher (something that is Neville's) could indicate that Neville isn't going to be coming back to WWE anytime in the near future.

11 11. Forced: Enzo Amore

Enzo Amore has only been on the main roster for a year and he has managed to make himself a number of enemies already. While the former football player puts on a persona where he acts like he doesn't care about the hatred that people feel for him right now, at some point it will get to him.

WWE isn't going to allow Enzo to be the main face of 205 Live forever, he has already become stale and once he loses that Championship he will be just another name as part of one of WWE's lowest-rated shows. Amore's only talent is that he can work the mic so he wouldn't be missed that much if he does find himself being forced out the door in the coming months.

10 10. Quit: Nia Jax

Nia Jax is one of the most dominant female wrestlers that WWE has ever had the pleasure of signing. The fact that she is related to The Rock has also worked in her favour over the past few years. Despite that fact, it hasn't been enough to ensure that WWE uses her correctly.

Nia has hinted that she has had a problem with her position on the card for a number of months now. Ahead of TLC she was said to have had an issue with losing to Sasha Banks once again. At some point, WWE must realize that if they don't put the Championship on Nia or at least give her a meaningful storyline, then she will walk away. She isn't like every other woman on the roster who are just happy to be there. She is too ambitious for what WWE appears to have planned.

9 9. Forced: The Undertaker

Many thought that The Undertaker's career had come to an end at WrestleMania 33 when it was beautifully wrapped up following his defeat to Roman Reigns. Since then The Deadman has undergone hip surgery and is now set to return to WWE TV for the first time since WrestleMania as a part of Raw's 25th Anniversary in a few weeks time.

It is highly likely that Undertaker will set up a final WrestleMania match where he will then be forced to walk away from the company for good. Rumours suggest that Vince McMahon could finally get his dream match between John Cena and The Undertaker. It is time for Taker to bow out. After one of the biggest matches of his career, it could be the perfect time for him to go.

8 8. Quit: Daniel Bryan

Daniel Bryan was technically forced to walk away from WWE back in 2016. It was reported that WWE doctors refused to clear the former World Champion for an in-ring return, so he was forced to retire.

Bryan has been able to return in a non-physical capacity over the past year, but it seems to be building towards a match between Bryan and SmackDown Commissioner Shane McMahon. Current reports suggest that the WWE doctors haven't changed their opinion on Bryan and are still not willing to clear him. Bryan desperately wants to wrestle again and since his contract with WWE runs out in a few months time, if WWE isn't willing to allow him to wrestle then he will return to the Independent Circuit and continue to do what he does best.

7 7. Forced: The Big Show

The Big Show hasn't been seen now for a number of months. In fact, ever since he put over Braun Strowman in their brutal steel cage match. It was thought that this would be Big Show's final match as he put over a new giant in the company. But following surgery, it seems that Show is waiting to return to the ring once again.

The WWE Universe have expressed their desire to see the former World Champion retire before and Big Show might be pushing his luck after hip surgery. 2018 could be the year that a number of WWE legends decide to hang up their boots and it could well be time for The Big Show to exit the ring one last time as well since he is only going to be used as a talent enhancer this late in his career.

6 6. Quit: Chris Jericho

Chris Jericho's contract with WWE is quite a strange one. His most recent one has expired, which could be why he is taking part in one of the biggest matches of his career outside of WWE against Kenny Omega at Wrestle Kingdom 12 next week.

Jericho will return to WWE at WrestleMania because it's just how Y2J operates. At some point, even Jericho needs to admit to himself that he can do better. Jericho will get a taste for NJPW and see that their talent are able to perform at a much higher standard than WWE because they aren't forced to follow as many rules. Even he could be seduced into that kind of life and who knows, this could be one of the best moves of his career. After all, it was revealed last year that all Jericho wanted to do was wrestle. He didn't even care about being on TV, so this could be a much better way for him to do it.

5 5. Forced: Goldust

Goldust is a veteran in WWE and was once considered to be one of the standout stars in the company throughout the Attitude Era. Sadly he is now the final member of The Rhodes family in WWE. After he lost his match to Bray Wyatt a few months ago and Wyatt wiped off his face paint, his career inside the squared circle is all but over.

Goldust hasn't been given anything decent to work with when it comes to storylines in a very long time. He has been a star that has been hinting at retirement for a number of years as well. The next 12 months could be the right time for him to finally make that decision when it comes to his future.

4 4. Quit: Brian Kendrick

Bad luck has spelled the end of many wrestling careers. Untimely injuries coupled with the ascension of other talents can mean the writing is on the wall for certain stars. In a match with fellow Cruiserweight Hideo Itami, Brian Kendrick was hit with a GTS that unfortunately caused serious facial injuries. While recent reports are better than initially expected, this type of injury could sideline Kendrick for the foreseeable future. With 205 live already struggling, this could be the injury that makes Kendrick expendable. This could make him use his new fame to find success in the indies. Seeing him return triumphantly only to fall back to obscurity is truly sad and he will surely want more at this point in his career.

3 3. Forced: Kane

Kane has had a career that has stretched over more than two decades. He is one of the biggest legends still currently in WWE and even he is aware that this could be his last big main event push in WWE.

Kane is set to face Brock Lesnar and Braun Strowman in a triple threat match for the Universal Championship at The Royal Rumble. Despite this, a career in politics could come between him and his desire to continue wrestling since he has run for a mayoral seat in Knox County. Kane has nothing left to prove in WWE and it would be something of a storybook ending if the company allowed Kane and his "brother" The Undertaker to finally hang up their boots and walk away together.

2 2. Quit: Rusev

Rusev has been on a shocking run over the past year and is still without a win on Pay-per-view in 2017. It is hoped that this picks up in 2018 now that he is part of a tag team with Aiden English and they are becoming more and more popular with the WWE Universe.

Despite this, it doesn't look as though WWE is willing to give them the push they deserve just yet. Rusev is very outspoken on Social Media and there have already been rumours from earlier this year that The Bulgarian Brute was thinking of quitting the company along with his wife Lana. It is unknown if he still feels the same way, but if he isn't given the push he deserves in the Tag Division in the coming months, then it would be hard to argue with him wanting to leave the company.

1 1. Forced: Sheamus

Sheamus is a former World Champion and a three-time Tag Team Champion with Cesaro. The duo were forced to drop their Championships to Seth Rollins and Jason Jordan on Raw this past week, following reports that Sheamus has been struggling with spinal stenosis for the past few months.

This is particularly serious considering this injury forced WWE Hall of Famer Edge to retire from WWE back in 2011. Sheamus is being monitored by WWE, but if this gets much worse he could find himself in the same position as Daniel Bryan. This means WWE doctors will likely refuse to clear him to compete and then he will have no choice but to walk away. Sheamus has been performing at the highest level now for a long time. Perhaps what is needed here is a short hiatus.