Cortana is gone in my view, the havoc nuke blew up and John was saved by her, but dr Halsey and cortana where like twins in a way, cortana was created from the dr. So if she created cortana it can be done again, plus all cortanas "logs" memory's will have been logged everytime she entered a consol? So she could be restored, if I am honest I'd like to see how chief plays out with out her, halo, halo2 , halo3 and halo4 all with her, he's just lost a friend and I think this could make a good story. Ether way, she's past her deteration time and rampancy was well and truly taking over her(mind it saved you tho!) lets see how this plays out.
-Jay
