Problem here is the Music Plaza stage is run by Universal Studios Florida Production Group and utilizes the Sound Stage parking lot for the Stages for everything regarding event parking, such as Talent tour buses, Equipment tour buses, catering, etc, etc. I believe booked talent for concerts also are given access to SS22A, which is basically the grooming area so they can have their team make sure they look the way they want to on-stage. Most can probably do this in their buses, but it's nice to have the option in case something goes wrong or in case they prefer that.
Of course you could theoretically make it work, but they would need to probably park talent on a far more sketchy Celebrity Circle, which any random person could stumble upon. You'd also need to build a small USFPG building run building back there next to the stage for anything they may need to run an event such as a concert.
Realistically, Universal is going to have no interest in doing all of this. They're way more likely to get rid of the stage without replacement imo. They've already figured out how to make Mardi Gras work without the concerts by adding a ton of F&W and they're doing less and less of them anyway. The only other time the stage is used aside from them is during private events (which is a decent amount, but normally it's just a DJ who could be in a much tighter space anyway) and the few times of the years Fallon has come or they film for something such as an Awards show (the filmed something for the Nickelodeon Halo Awards in 2016 or so) or that one time when One Direction filmed a Christmas special that aired on NBC.