USF will follow Epcot's role in the resort. It won't be the most popular one, but it'll remain crowded thanks to its seasonal events. But yes, this is the park most in danger of being cannibalized by EU. And when I say cannibalized, I don't mean fully tank in attendance, just stagnate/lag. Epcot attendance lagged, but it didn't dip when DAK/DHS got their additions.
That's why WDW is emphasizing DAK as the next park for investment. I have the pleasure of visiting DAK after work each week, and it's pretty much a ghost town. SeaWorld/DAK/USF will be fighting for scraps lol
Worried to see what happens over the next year or so regarding ops. HHN's attendance level is roughly ~25-30K a night, and they can't manage that properly. I accidentally attended IOA on a Rock The Universe day and they were just not at all ready for those crowds. It's very impressive to see how WDW manages 45K guests at MK on an average day and Universal struggles with nearly half of that.
One thing Universal did really good, and no longer does as much (as well as Disney), are attractions that you can simply just go and experience with no wait. While they are not E-tickets, they take away some of the stress from having to either queue or do nothing at the park.