Nothing has been confirmed yet, despite the many rumours and common sense that Conor McGregor will fight at UFC 200. He's one of the UFC's most marketable athletes, and he's been very open about wanting to be there.
Perhaps it's a case of whatever Conor wants, Conor gets - but ahead of finalising the match-ups for the landmark event - Dana White revealed that McGregor will definitely be at UFC 200:
In thirty minutes is our big match-maker meeting, and we're really going to start building UFC 200.
You can't make people fight. Conor McGregor is perfect example. This guy is going to turn around and fight at 200 again, you have to have the burning desire to fight.
https://www.youtube.com/watch?v=_91txguTogo