Episode 16 implied that Emperor mind rape has been going on for some time. She has some connection with Lelouch from childhood, and she doesn't seem too excited about the nuke plan. She has too much unresolved plot to be killed off right now, so the logical sequence of events are that Orange will (probably on accident) break her Geass. She will get her memories back and turn on Britannia.
Hopefully that big gun on Mordred takes down something on the way out. Maybe the Avalon? Personally I'm hoping she is the one to kill that psycho bitch Nina.