+ Studio production buildings + large back of house operations. While there will be some back of house operations in the new area, not all of it needs to be 100% duplicated (eg creative, marketing, hr).
Additionally, I think Universal could have packed way more in to their original area had they planned a bit better. Look at how much land Portofino occupies (and # of rooms) compared to Adventura, Sapphire Falls, Cabana Bay, Endless Summer, and Surfside... I think think they'll be in the mindset of constant expansion and conserving space.
I think it's very possible they could pack 6 tall hotels, 2 parks, and a water park into 500 acres. I think it will look a lot different than the old land though (more planned out rather than evolved).
Good thing for us...bad thing for the people in the area who always be dealing with construction.