Smigone

Imo, Cortana will return in a human-like form. I don't think that she left part of herself in chief's armor-remember that chief had it removed. The composer is destroyed, so I doubt that would be a major factor in the upcoming games. But John keeps his promises, and I doubt he broke one he made to Cortana. He will be given a temporary Cortana from Halsey and will then be confronted with the possibility of bringing the old one back.