I expect to see more "enclosed" lands in themeparks moving forward. Diagon Alley is basically "Gift Shop Land". You go in to look at it and ride the ride, but before you exit you have to pass by almost every shop, no matter where you go, there's no way to avoid walking past a shop more than once. It's ingenious design.
Not only that, I think it has a positive effect on park capacity and throughput on the streets and logistics. You can essentially divert people to a whole land that does not operate within the confines of the exterior park experience.