Brock Lesnar is a perfect example of the classic economic principle of "supply & demand." Because he wrestles so infrequently, the "supply" of Lesnar is low. But people really want to see him, so the "demand" for Lesnar is high. Which makes any appearance he does an event that is sure to sell tickets and fill the seats! And one such event has already been announced for Friday, March 10th, 2017 in Buffalo, New York.
That is where, and when, The Beast Incarnate will be fighting in a house show leading up to WrestleMania 33 on April 3rd. There is no word yet as to who his opponent will be for the show.
And in case you were wondering about his next non-televised appearance. Brock is scheduled to go up against Rusev in just a couple weeks on December 3rd, 2016 in Mexico City.