And the more I have thought about this, the more convinced I am that it's just not a big deal.
When Disney built WDW, it could not have happened without RCID. The local governments thought it was a loftly idea, but none of them had the influx of cash to be able to build the roads, electrical grid, water grid, fire and safety systems, and all the other things that go with a development as big as WDW was going to be. They would never have been able to afford it, and WDW would never have gotten off the ground. It was NEEDED if Disney was going to build this thing.
Today is a VERY different world. These things exist now. No one has to build them. Yes, new roads may need to be built; but there are ways for companies to do that (heck, the company I used to work for paid to have a traffic light installed - the first one in the city we moved into - it was a BIG DEAL). But the sheer size of the project is not that scope anymore, and even for a new gate, the counties are well rehearsed in how to handle it.
I am sure Disney benefits from RCID - otherwise, they would have moved to dismantle it years ago. But in general, Disney has always offset its buildings with undeveloped land. They have had to meet building codes anyway. They get some tax benefits, but I am not convinced it's even a MAJOR deal for them if RCID is dismantled. More like a minor annoyance and tick to their pocketbook; but nothing they can't afford easily.