She really does die, though. That's why my friend Karsyn and I (We are both girls) cried at the end of Halo 4. On top of that, I look almost exac tly like Cortana. No joke. She was my favorite Character because I could relate to her feelings easier than the Chief's.
I was shocked by the ending of Halo 4, but by the time the final cutscene was over, I had come up with at least three different theories explaining how Cortana might not be dead. Even today I don't believe she's going to stay dead for long.