"The ultimate X-Men ensemble fights a war for the survival of the species across two time periods in X-MEN: DAYS OF FUTURE PAST. The beloved characters from the original 'X-Men' film trilogy join forces with their younger selves from 'X-Men: First Class,' in an epic battle that must change the past - to save our future."
Matthew Vaughn has already presented ideas for the sequel: First Class is similar to Batman Begins, where you have the fun of introducing the characters and getting to know them, but that takes time. But with the second one, you can just get on with it and have a rollicking good time. That’s the main difference between Begins and The Dark Knight. I thought it would be fun to open with the Kennedy Assassination, and we reveal that the magic bullet was controlled by Magneto. We will only have one more new character. I won’t say who he… I won’t say who he or she is! But we will only be bringing one more new character in, because, I think, as Professor X is in a wheelchair, Magneto needs to have a nemesis he can fight with. Someone that will be his equal. I know who it is. It would be nice if I could say something, but I can’t, mate! I'd like to set it in the latter part of the 1960s where you’ve got The Stones, The Beatles, Flower Power."
Matthew Vaughn stepped down as role of director in October 2012, and it had been rumored that Bryan Singer to replace his role. Later, in the same month,it was announced that Bryan Singer will direct the film.
James McAvoy expressed interest of Professor X getting really messed up in the sequel and speculated that a third film could show his transformation into the Professor X in the triology played by Patrick Stewart: "He can't just become the guy that we saw in the first three movies. He just had two major things happen to him. He's lost his best friend, essentially, and he's just been paralyzed from the waist down, which is just a huge, huge blow to his considerable ego. So he's got to deal with that... You've got to deal with that. I don't care if he's a superhero and has brain powers or not; he's just had a huge part of his physical life taken away from him, by someone he cares about more than anyone else. So he's got to deal with that."
Michael Fassbender has said that he is "very excited" about the possibility of a sequel: "We worked very hard. It was a very trying time. Thank god, James is a good guy a very smart guy and he's a very practical guy. Matthew's great because he makes films as a fan. There's something like a nine-year-old boy in him when he's making a film. He's very much into characters and allowing the characters to drive the plot and the plot to drive the action film, as opposed to action driving the film and threading in some sort of a plot. It was a very rewarding experience, so hopefully we'll get the same team back again."