Considering they also talk about her being one of the first hybrid AIs made from neural tissue, they may be able to find a piece of that tissue and rebuild her from that. She will be completely out of it for Halo 5, forcing Master Chief to battle his own demons and have a little more difficulty ascertaining the best course of action. Maybe at the end they will bring back Cortana and all that she was, then again their may be a heavy toll on her index of memories from her actions versus the Didact, causing her to be an amnesia stricken Cortana. That's my thoughts/guess anyways.
