I hope she comes back, I hope they all do! It'd be a perfect ending to a fabulous movie series. I loved the last one, replacing the first movie as my fave.
Oh and I don't know how much the discussion has gotten into Snape, but I believe he will be the one taking over Hogwarts at the end of the last book. He did what he had to do in order to save Draco from becoming evil like his father. As of now, Draco is simply following what the elder Malfoy has filled in his head!! I also think Harry has a good chance of dying in order to prevent Voldemort from having the slightest chance at returning cause I do think Harry is a Horcrux.