X-Men First Class Sequel title Revealed

Bryan Singer executive producer of XMen First Class,announced that the sequel for First Class will be called - X-Men: Days of Future Past.

Mathew Vaughn returns to direct the sequel,and will be joined by Fassbender & James McAvoy reprising their roles as Magneto & Xavier.
The story is said to be very ambitious and Bryan said that the movie plans to expand its universe.As you might know X-Men is in the same universe of The Avengers,Spiderman etc. (Marvel Universe) .Could there be any possible crossovers in the future?