I know they won't take out WaterWorld but with the recent demo of the Cartoon Store and Shrek 4D closing, it opens up a large space for use.
I can see them add a smaller scaled down version of Diagon Alley with a much smaller Gringotts attraction. They can easily add a London facade where Shrek 4D currently sits. and then have Diagon alley extend to water world, where the show building will be for Gringotts.