According to James McAvoy, the younger and older Xavier's will never meet.
While we definitely know there is a time travel element in X-Men: Days of Future Past, it isn't ultimately clear how the older Xavier and Magneto figure into the story.
Bryan Singer is directing from a screenplay by Simon Kinberg, based on Chris Claremont and John Byrne's comic book arc that centers on an alternate future where mutants are hunted down by Sentinels.
X-Men: Days of Future Past was released May 23rd, 2014 and stars Hugh Jackman, James McAvoy, Michael Fassbender, Jennifer Lawrence, Halle Berry, Nicholas Hoult, Anna Paquin, Ellen Page. The film is directed by Bryan Singer.