I wonder if Disney did the GOTG retheme of the California Tower of Terror in order to beat Universal to the punch on a Marvel drop ride.
You're idea could idea could work for an idea I had about putting a roof over part of MSHI. The tower could look like an Avengers tower from underneath the roof and have a drop ride in it, but when you exit the drop ride you could be given the choice to exit at an area on top of the roof and be taken to differently themed area.
An idea I had for the Marvel area if the skyline from other areas of IoA, the hotels, or the waterparks isn't a problem is that they could put a roof over part or most of the Marvel Superhero Island and build an area based on New Donk City from the Mario Odyssey game. The roof either would or would not have walls attached to it going around the area of MSHI that would have a roof above it. This would provide more shade to IoA and allow more attractions to be added to IoA without getting rid of any Marvel stuff. The attractions in the New Donk City would probably have to be lightweight, so they might be VR rides. If having heavy attractions isn't a problem, parts of the New Donk City could also be used for storing things. The New Donk City level seems to have a crane as part of it so it could make sense to have some sort of crane as part of the area that lifts things up to the area for storage or lowers them down.
The Hulk coaster would probably not be under the roof except maybe part of it and that part might have a covering around it so that it's not seen as it goes through the area under the roof and prevents outside light from coming down into the area. So, it would be like the section of Rip, Ride, Rockit that goes through the New York area, but maybe have a covering around where the coaster track is so that it would seem like the coaster is going through a tunnel from the point of view of a rider.
If the roof has walls around it and can make the area very dark, it can provide an interesting difference to much of IoA or even another part of MSHI if the roof doesn't go over a substantial part of MSHI. Having it possible for the area to be dark could be interesting for Halloween as well. For the future, if Disney ever buys the Marvel theme park rights or Universal decides to change the theming for some other reason, something interesting that can be done is change the area under the roof to be themed after Batman's Gotham City and change the area on top of the roof to Superman's Metropolis (Gotham is often shown as being darker than Metropolis in recent movies). Relatively small theme park areas are reportedly being constructed with similar aesthetic ideas in an indoor theme park in the Middle East.
Warner Bros. Plans To Build Gotham City For $1B Abu Dhabi Theme Park | Deadline
If it's not rethemed to Gotham and Metropolis, it could still be rethemed to a city during two different two time periods such as day and night or two times decades apart or the two areas could be rethemed after two different other cities.
It seems that Unviersal at one point had an idea for building facades that look like large New York City buildings in the IoA area. You can see it in the pictures titled 'Universal City Overview' here- parkrumors.com/universal-royal-egyptian-resort/