6. Xavier Might Die (Again)
The biggest inference taken from the Apocalypse revelation - assuming, as everyone seems to be, that Singer will focus on the most famous, and potentially the most bountiful or a sequel to Days Of Future Past, in the shape of Age Of Apocalypse - is that at some stage, Charles Xavier needs to die. Whether they follow the actual events of Age Of Apocalypse, and have Xavier's disturbed son Legion travel back in time from the future to attempt to assassinate Magneto in order to help realise his father's ultimate goal of mutant-human co-existence, prompting Magneto to change his tract on human-mutant relations, remains to be seen, but Xavier's death is an unavoidable plot detail. With Magneto's guilt for Xavier's paralysis already well-established by the end of First Class, it would be a reasonable leap to assume that Xavier's murder - particularly a selfless act to save Magneto himself - could prompt the kind of decision that sees Magneto abandon his agenda for mutant superiority in Age Of Apocalypse. With the events of that run inspired by Xavier's death, having that event happen at the end of Days Of Future Past fits the timeline.