Let me be the first to say that I was certain and sure that RR would never fight again after the Holm KO. In a sense, I was right because she didn't really do any fighting against Nunes.....
That said, Lesnar never fights again. I think the UFC is going to be more cautious with fighters who have popped. They take a hit every time, and they're continually fighting for the legitimacy of the sport. Everyone who saw Lesnar knew he was on something(s) for a very very very long time. Maybe I'm wrong, but even the revenue might not balance the bad press. And who even knows if Lesnar wants to fight.