Her situation is pretty much the same as Spock's in Star Trek and Into Darkness.
I thought it was now generally accepted that the Abramsverse
exists in a parallel timeline, rather than totally erasing 150 years of Trek history. I'm sure I remember an interview where the writers of ST'09 confirmed this was their intention.
I certainly have no problem with Trek characters popping across alternate universes, since their universe of origin is still intact and carries on without them.
As for other Trek characters traveling back in time along their own timeline
and changing the past to invalidate their own existence and surviving
- are there any other examples? I'll need to do a little research I think!
Do we know for sure that there is any difference? Ignoring novels and Word of God for a moment, it's as much a possibility that the "Yesterday's Enterprise" timeline continued on after the E-C flew back into the rift and the -D was destroyed as it is that the Primeline was erased when Nero and Spock went back in time.
One could interpret YE like this: That the war timeline is the original, since the Enterprise-C skipped forward in time as a result of it's battle and then was sent back 22 years later, creating the TNG history which we know.