When X-Men DOTFP came out people were asking a lot of question one of them is what have this film done to the other X-Men films so, the actions of the 1975 X-Men have apparently changed the future dramatically. Jean's alive, Cyclops is alive, the sentinels haven't overrun the earth and Wolverine's a teacher. At the very least, the events of X-Men: The Last Stand didn't happen the way they did, and the events of X-Men and X2 are now pretty suspect as well. But Professor X does remember that a time-travelling Wolverine came to help him out. So everything in X-Men: First Class happened, and everything in the 1975 era of X-Men: Days of Future Past happened, and from that point on all continuity has been rewritten so that different stuff happened. Which does have the positive outcome of erasing X-Men Origins: Wolverine, at least.
Fox have change X-Men timeline so the other X-Men films maybe happend but it happend in a different way or never happend and X-Men first class and X-Men DOTFP is the new timeline for the X-Men and with X-Men apocalypse will be the next X-Men film which will maybe be set in the 1980s which will be release in May 18 2016.
