If Missy isn't the Rani, perhaps she is a new Time Lady all together. After all, the possibility of new Time Lords is entirely plausible now that Gallifraey falls no more. Yes, Gallifrey is locked up in a bubble universe, but it is possible to break through these barriers. The Doctor did it in the Doctors Wife, after all. If this is the case it can go one of two ways. Either this new Time Lady will love the Doctor, and will be trying to help him in saving those he has killed, or else theyll despise him and be attempting some form of revenge. Well go with the latter. As noted, the Moff loves creating empowering female characters, so an all-powerful Time Lady would be right up his street. He has created iconic foes in the past - the Weeping Angels and the Silence - so it is possible that he would attempt to create a dastardly Time Lady to rival the Rani and the Master. If Missy isnt a new Time Lady, the Moff will probably introduce one ultimately anyway. Watch this space.
