THR is reporting that the upcoming X-Men: Days of Future Past movie from 20th Century Fox will feature James McAvoy and Patrick Stewart as well as Michael Fassbender and Ian McKellen.
Stewart played an older Charles Xavier in the first 3 X-Men movies while McAvoy played a younger version of the character in the more recent X-Men: First Class. The same goes for the Magneto character. McKellen who played the Master of Magnetism in the first 3 X-Men movies will be returning as well as Fassbender who played Magneto in First Class.
The orginal Days of Future Past storyline in the Marvel comic books which was written by Chris Claremont dealt heavily with time travel so it makes since we would have older and younger versions of these core characters appear in the movie if the storyline is anything like that in the comics. Days of Future Past is a sequel to the 2011 X-Men: First Class movie which was kind of a prequel to the first 3 X-Men movies. This latest X-Men movie will be directed by Bryan Singer who also directed the first 2 X-Men movies and was a producer on First Class.