Like what? Your proposal of a 50/50 land, one of which is LA, doesn’t exactly sound better than going the Diagon direction; but I may be misunderstanding!
I think the question to what happens with Springfield/The Simpsons, is in itself what happens to the current Studio Tour plaza. If nothing is done that allows the park to expand their foothold to swallow the plaza; then they find themselves limited by the nature of having to cater to both that of the secondary exit to Potter and the flow that is present as people go to the Studio Tour (And those who go into the lower lot in turn).
Echoing
@Wesker69--and being a bit more broad, I think a project that combines both Studio Tour Plaza + The Simpsons Ride, Cleetus, Kwik-E-Mart, and the restrooms would give them options in being able to improve and betterment the flow and navigation over there. A combined Show + attraction, with a relocated Studio Tour feels like the right play in the longer run.
Once Hollywood Drift finishes, and once they get operations occurring for the hotel; one of the last true big holes USH will have lies with live entertainment. I genuinely believe they need to replace The Simpsons Ride with a live entertainment venue that can have something that'd make sense for the park.
Untrainable, The Bourne Stuntacular, that once planned Wolfman stunt show for Epic, hell even Sing Live would do something to help. It is a glaring and prevalent issue that I believe matters on a larger element.
I get all that but like... from a financial and business standpoint, more HP is what's going to earn them more money. I rather see a version of Dark Universe but that won't be as profitable as HP. It sucks but that's the safe option and the one they're most likely going to go for
Oz is right there. I think USH needs to diversify what IP's they have, and more Potter feels like a incredibly bad choice in the long run.