Intercontinental Champion Roman Reigns was pulled from two weekend shows and is unlikely to appear on Monday Night Raw (he wasn't advertised for the event).
The reasons for Reigns' absence are unknown, but it should be noted that he missed nearly a month with the mumps virus. He had to get pulled from the TLC pay-per-view card and was replaced by Kurt Angle in The Shield's match. A month later, the faction finally reunited and defeated The New Day at Survivor Series.
It would be a huge blow to the WWE if Reigns had to miss extended time. The Royal Rumble pay-per-view is a month away, and he's finally received more cheers and ovations from the audience. A reunion with The Shield and his feuding of legitimate heels have made Reigns more popular, so a long absence could lose him valuable momentum.
Without Reigns for tonight's episode of Raw, it'll be interesting to see how some of the feuds and matches unfold. Reigns and his Shield partners have been feuding with Samoa Joe and The Bar for a while. Perhaps Strowman's feud with Kane gets put on hold tonight, and maybe he faces Joe.
WWE has been excellent at finding ways to make last minute changes when a superstar has to leave town. A couple of months ago, Kevin Owens had to leave SmackDown's South American tour, and he was promptly replaced by Triple H. Nobody complained about Angle replacing Reigns at TLC, either.
We should get an update soon on the reason for Reigns' absence, and can only hope it isn't anything long term. The man has worked hard enough for the spotlight.