Originally Posted by BMM
That's exactly how they would reboot it, using Days of Future Past as a spring board, if they want to. Or they could just reboot it regardless. Fox is going to have to figure something out. The First Class cast is contracted for one more film, and I don't envision the novelty of having the original actors back lasting much longer.
Being contracted for one more film does not guarantee that they will appear in another X-Men movie. The new cast members of X3 were signed for 3 films but most of them aren't coming back for this movie and so far, only appeared in X3.