During San Diego Comic- Con MTV sat down with Simon Kinberg who was the writer of X-Men Days Of Future Past. And is also working on the new Fantastic Four movie and Disney's Star Wars: Rebels cartoon.
Here is what Kinberg had too say, in terms of the roster for X-Men: Apocalypse....
"I would say in terms of making any character decisions on ‘Apocalypse’ is, we set back the clock on ‘Days of Future Past,’ so a lot could have changed from that point in 1973 forward, meaning people could have been born earlier,” Kinberg said. “The whole world changed after those events. Things that were represented even ‘X1′ and ‘X2′ and ‘X3′ wouldn't have happened in quite the same way".
So basically from this point forward any Mutant could be in X-Men: Apocalypse, since as Kinberg said they set the clock back. So it is possible for Angel to be in Apocalypse, will they use him... Who knows but it would be very cool.