I think Stitch needs to go. Rip down the entire experience. No more rebranding and no more Pixar.
The difficult thing is that Disney doesn't make memorable character movies like they used to. I can't think of any that are really worthy of a ride outside of Pixar and that is a MAJOR problem for them. However, this is Tomorrowland so there is nothing that says it has to be based on a character or movie. It can be independent of it all, like Space Mountain.