Originally Posted by BobJM
It's not that important. She's not in this story, she's either left the Brotherhood/dead. It honestly doesn't matter.
And, should her character be needed again in a future flick, a simple scene or line of dialogue can be created for explanation. But that can all be done later, doesn't need to be seen in DOFP.
How do we know for sure she is 'not in this story'?
If they are following the comic and having past Brotherhood try to assassinate a political figure, Emma could easily fill the role that Destiny took in the comics. I can't see 70s Magneto operating on his own.