All of Nintendo (Mario, Zelda, Pokemon, Donkey Kong, Star Fox, Metroid, Kirby, Animal Crossing, etc) is equal to Potter's draw IMO. Collectively, it's a gigantic deal for Universal. Mario and Pokemon are definitely HUGE in terms of potential merch/food/beverage sales.
Kong and F&F will draw in big crowds because they'll be quality E-ticket additions. You know, the kind WDW used to get (Splash, Space, Big Thunder, ToT, Kilimanjaro).
The IP doesn't matter at this point. Potter brings people in - the remainder of the parks will keep guests there and let them know what Universal has to offer.
Hollywood Studios WILL drop. When LMA, Indy and either Mermaid or B&TB close within the next 1-2 yrs, attendance will start to decline. They can't sustain growth with only 8-10 attractions forever. Even with Universal doing the heavy lifting.