With Bryan Singer now on board officially to direct X-Men: Days of Future Past, following the departure of Matthew Vaughn, more news on the sequel to X-Men: First Class is starting to be announced. Singer tweeted out that James McAvoy, Jennifer Lawrence, Michael Fassbender, and Nicholas Hoult would be returning to their roles. Those were all expected. What comes as somewhat of a surprise though is Patrick Stewart and Ian McKellen joining the cast.
Those two of course were featured as Professor X and Magneto in the original X-Men trilogy. That they will be appearing in Days of Future Past fits with the idea that the film will focus on different points in time as described in the synopsis below.
The storyline alternates between present day, in which the X-Men fight Mystique’s Brotherhood of Evil Mutants, and a future timeline caused by the X-Men’s failure to prevent the Brotherhood from assassinating Senator Robert Kelly. In this future universe, Sentinels rule the United States, and mutants live in internment camps. The present-day X-Men are forewarned of the possible future by a future version of their teammate Kitty Pryde, whose mind traveled back in time and possessed her younger self to warn the X-Men.