(no but really people shouldn't read this thread if they haven't read the book...they should go read the book because it's awesome)
Anyhow, do you think that she will be "back?" What with time travel, and the whole changing-of-the-past concept already introduced, it's at least feasible that people who die may resurface further down the track. Do you expect to see Zoe again? Would you even want to?
Personally I found her to be very compelling; legitimately psychotic, but at the same time really damaged and therefore sympathetic. I would've liked to see her mental health and past dealt with. And the rich potential thereof is what has me wondering if she might possibly come back. It'd be at least as shocking as seeing her go.
I also find it interesting that she died at all. As has been brought up in interviews, Irina may have had a reason to kill her (after all, she demonstrated her ability to take nonlethal/incapacitating shots if she wants to), so maybe that will be addressed... but either way, yeah... I don't know how many people out there are reading this book or will even see this thread, but I figured I'd toss it out.