Was thinking of something like this:
View attachment 29159
I think DU's issue is that it has very little to do compared to the other lands. There's really only 2 shops, one of them being an exit gift shop. DU is also beautiful at night and I'd love to see it Diagon-esque experience with a side side in perpetual nighttime.
By doing an expansion like the one above, Universal can add an additional shop and snack stand, and an immersive walkthrough experience. Along with an indoor alternative for the monsters to roam around when it's raining outside.