In a recent interview James McAvoy said he’d “be up for it” (although he is contractually obliged to make more), and thinks it should be “cleverer” than just reverting back to Xavier and his X-Men vs. Magneto’s Brotherhood.
From Total Film:
“I’ve spoken to Matthew [Vaughn] about ideas, but I can’t tell you what they are because they may or may not be the story. One thing I liked about our one was that it was different from the other three films where the X-Men are the good guys, Wolverine’s figuring out who he is and Magneto is the bad guy.
“This was a completely different thing. Magneto wasn’t a bad guy, we were friends. We’re now set up to go back to the way the other movies are, so we’ve got to try to be cleverer than that.”
Charles and Eric didn’t part ways on the best of terms, but you could see them sitting down for mutant/human-related discussion in the next film (Xavier doesn’t really have an option with the sitting bit). In X1 Xavier said Magneto helped him build Cerebro, and while Beast was the inventor in First Class they need to rebuild it at some point, and it’ll be hard to build that vast spherical room in Xavier’s basement without help from a metal manipulator.
While promoting the film in June McAvoy said he hopes Xavier “unlocks something in his head – maybe he can’t keep the voices out or something” and “his journey could be about getting himself out of a mess.” Matthew Vaughn also said as “Professor X is in a wheelchair, Magneto needs to have a nemesis he can fight with. Someone that will be his equal”, so we could be introduced to a powerful new villain.
Vaughn is currently developing a few movie projects with Kick-Ass comic writer Mark Millar, but I can see Fox aiming for a 2014 release for the sequel. If that’s the case we should start hearing things next year.