With all they've gotten here and all the mutants, I wonder if we'll get to have a sneak cameo appearance by Proteus- acting as a deus ex machina against Apocalypse? Very, very doubtful as their stories never really crossed. But then they have shifted a lot of things around to make these films work in this timeline anyways.
Regardless this trailer looks pretty awesome.
X-Men: Apocalypse hits theaters May 27th, 2016.