There is still room for hotels or a waterpark on the east and south sides of this contiguous property. Plus, they also have the ~400 acres of satellite parcels that they can build on as well. Building to the east of the parking lot will need to be postponed for a few years though, as there is still a bit of clean up to be done before they get the greenlight to build there... which probably explains why the site has been set up in the way it has. It's also possible a water park could be built directly next door to the new park, on the west side of the parking lot, sharing its land... But from what we heard about them saving entire sections of space for adding new "worlds" down the line, I'm thinking they want to keep that entire space for the new park alone.