Bryan Singer has confirmed via his Twitter account that Patrick Stewart (Star Trek: First Contact, Excalibur) and Sir Ian McKellan (Apt Pupil, The Lord of the Rings trilogy) are set to reprise their roles of Professor X and Magneto, respectively, in the new X-Men: Days of Future Past film. They will be starring alongside X-Men: First Class returnee’s James McAvoy (Wanted, X-Men First Class) and Michael Fassbender (Shame, Blood Creek), who play Professor X and Magneto, respectively.
Days of Future Past is a time travel story that will bridge the two X-Men universes and open up possibilities for an X-Men 4 with original cast members of Patrick Stewart, Ian McKellan, etc. as well as leave the door open for more past focused entries featuring James McAvoy and Michael Fassbender. Here is Bryan Singer’s original Tweet, if you don’t want to click the link:
As more info becomes available, I will keep you posted.