Just a couple of thoughts during this dark times to keep things in perspective.
While I don't "know" anything on the ToT repurposing topic and I haven't specifically asked any friends (to be honest, I'm afraid of what I may hear if I do ask), I want to take a step back and remind everyone of some important timing milestones on the horizon if this were to turn out as true at WDW.
I am not aware of any compromise between Disney and Universal to date regarding the use of the Marvel IP east of the Mississippi. There were rumors about Disney being willing to do a little quid pro quo with Universal in regards to leniency using the MCU IP in an effort to further strong-arm Fox on their theatrical Marvel content. At the time those rumors were flying, the arrangement was going to be Universal getting to put the MCU likenesses into their parks in exchange from getting any Fox theatrical control IP out. If such a deal were to take place, perhaps official Universal approval for use of any Marvel IP not currently in use in Universal land by Disney Parks in Florida could've been exchanged.
I'm also not aware of any other Disney/Universal agreement having been made separate from the above rumor for WDW to use any Marvel IP in the parks.
Now, we do know that Disney Parks in Orlando has been trying to test the waters on their own (without Universal's approval) on where the boundaries of the contract are. There were tests with the monorail with Marvel IP that were met with Universal reaction. There were tests using MCU based IP (in this case a poster in DHS) minus the Marvel name that didn't cause a Universal reaction. The boundary was again pushed by Disney with the use of MCU characters (in this case GoG ones) in the same park that also did not cause a Universal reaction.
So, if ToT is going to morph into Guardians Tower, we should be able to see the writing on the wall soon enough.
Hulk is the first Universal attraction to undergo a life change since the rumors of collusion between Disney and Universal first appeared last year. When it reopens, if you see the MCU represented instead of a cartoon based Hulk - then there's more fuel to this fire.
If Hulk is reborn without Mark Ruffalo or his likeness, Guardian Tower in Orlando would be a huge gamble for Disney to make without an agreement with Universal. By the time such a make over would take place, GoG's MCU IP will be 100% represented side-by-side with the rest of the Marvel MCU Avengers roster in the upcoming Infinity War films.
Universal letting a poster and a few limited meet-and-greets with IP they control slide in Orlando is completely different then allowing them competition down the interstate gear up for a multimillion dollar E-ticket and let them advertise it. If they were smart (which they most assuredly are), they would sit back and wait for the Disney to start work on it and as soon as it is set to open - then raise the matter with a cease and desist.
Would Disney be arrogant enough to attempt such a move without prior written consent from Universal (or Major League Baseball)? We all know unfortunately that arrogance is something they have plenty of (hence the years of neglect, upcharge events, and general contempt they have for their guests these days).
Just as I said a few weeks ago about the resort fees, don't let the fact of whether or not these rumors may or may not come true make you angry. It's the fact that they are even considered that should be enough to do so.