Theory

There is a particular scene that may suggest that this is the last time we see a certain mutant (at least until the inevitable reboot) on the big screen. This has actually been corroborated by the actress who plays the mutant, who happens to be Mystique.

As seen in one of the clips released, she will engage Apocalypse in close quarters. And that is obviously a bad idea, since she isn’t overly superhuman, especially for a superhuman character – at least, we can say that she is not in the same league with Apocalypse. And Jennifer Lawrence did say, at one time, that she may be done with the X-Men after X-men: Apocalypse (yes, she said differently after some time passed, but still…).

So, could this be her swan song? We believe it is, especially since she has a much more prominent role than ever before (even bigger than in Days of Future Past, when she actually fueled the entire plot). So we may see her heroically perish at the hands of Apocalypse.

Furthermore, given her past relationship with Magneto, her death will also convince him that Apoc is as bad for the mutants as he is for the humans – so, he will rebel. Because, let’s face it, Magneto AND Apocalypse are just too much to handle for a team of inexperienced X-Men.