I sound like a broken record by now, but I personally don't see us getting Diagon Alley no matter what and I don't think we have room. I'd love to see it, but I also don't, because I want Universal to invest in other properties, not JUST Potter, especially in our land deprived park. Works in Orlando, I don't think would work here.
I also don't personally think they can add enough attractions to the park to make it a multi day resort or experience. There's just not room without extreme modification of studio facilities, which we don't know how willing they'd be to touch them. Although it's possible. I can see them eventually removing some of the soundstages on the lower lot and putting in more rides IF they relocate them somewhere else. But even then, that will be an addition of around 5-6 more major rides after Potter, and I dont think that's enough to be a major hotel resort.