Waterworld as a IP has no legitimate value or incentive of future growth. The thing that matters, is that Waterworld, the UDX show, is one of the most popular theme park shows in the world; and it is a massive people-eater with the show runtimes.
Be with Waterworld, or The Purge: Dangerous Waters (or any other show that happens for seasonal purposes), USH needs this venue more than any other element, to stay as a show venue. Unless a new venue comes around for USH, don't expect this to be going anywhere until that moment comes.
They may be dumb by killing Animal Actors and Special Effects Stage at the exact same time, but they won't kill off Waterworld without filling in someting new.