Well, we have sort of a confirmation concerning Ghostbusters 3. Bill Murray, on the Letterman Show, spoke about the rumor/spoiler that he would appear as a ghost. Now, logically, that would mean he would have to be killed.
Bill had this to say: "I told them if they killed me off in the first reel I’d do it. So now they figured out a way to kill me off in the first reel."
Woah there Bill! Are you saying that's true?! He said no more about it, but now it can't be a "spoiler" because all of America knows it. Will Venkman "pull an Anakin" and become what he once vowed to destroy?