My issue with fans clamoring for (specifically) BttF coming back is that its future Hill Valley was.... Yeah, 3 years ago. It's a situation where the story dates itself. That's fine in a movie, but in a theme park it makes it look more like a joke.
There's more wrinkles to it than just that. In order to bring it back though, you HAVE to include Christopher Lloyd and Michael J. Fox. Unless they're strictly doing voices (or Universal will pay to de-age them), it would look unnatural for them to be there because they've aged out. Second, 2015 Hill Valley was a futuristic world that doesn't exist, which requires any visit to 2055 Hill Valley to be some over the top future beyond the movie. Basically, you'd require Universal itself to pitch a whole new movie when (looks a F&F) that's not really a forte.
BttF is amazing and a classic. It's thirty years old though. Yeah.
Get over it.