[Gorwingel]

I think that the demise of Saruman may be similar to the Scouring, with Wormtongue killing Saruman, but just in a different location. Maybe after they leave Gondor, after Aragorn has become king and all, they go through Isengard on the way back, and maybe Gandalf confronts him and then Oh I don't know, I just hope they handle it in a good way.