Spoiler alert: The sequel to X-Men First Class will be called X-Men: Days of Future Past. Fans of Chris Claremont's X-Men will already know that this means we'll be visiting a horrendous dystopian future, where mutants are basically stuck in interment camps and a mutant-hating regime rules the world. This is the result of an assassination of a powerful mutant-hating senator in the present day by Magneto's Brotherhood of Evil Mutants.
Producer Bryan Singer reveals this massive bombshell in the above video interview with IGN, in which he explains:
It's being written now and it starts shooting in a few months... It's going to be very ambitious. It's called Days of Future Past, and it deals with aspects of that comic but also some new things. I just don't want to give anything away. Matthew Vaughn will be directing, and we're very excited about that.
He also hints that they want to make the X-Men movies into a coherent universe, much as Marvel has done with its own in-house movies leading up to and coming out of The Avengers. Says Singer, "I think there's a strong desire to broaden out the universe. The X-Men universe on its own is every bit as big as the Marvel Universe. And I think it's time to reach out and explore it, and perhaps even bring some connectivity between the films, as Marvel's done so well."
At Comic Con, Collider talked to Jumper writer Simon Kinberg, who's writing the screenplay, and he said the movie would be "epic" and "mythic," and a bigger movie than the first one. He added: "It is unlike the other X-Men movies and yet very much a celebration of the X-Men movies."