It's important to understand that the Reedy Creek Improvement District (RCID) was established, in part, to ease the logistical and bureaucratic issues that Disney would have to deal with working with two different counties. If the RCID is dissolved, most everything that has infrastructure, legal, or regulatory requirements would have to be handled by both counties, in order to allow the park to have a set of consistent rules and services. (Imagine that Disney could serve alcohol in one half of the park, but not the other, because a liquor license was granted by one county, but not the other. Admittedly, if that were the case, then Disney wouldn't serve alcohol at all, but it illustrates the point.)
You say "handled by the county" as if it's a burden, but that's literally the purpose of government.
The real burden is now on Disney, who has to demonstrate to the governing body that any given desired improvement is worthwhile to be approved.
Part of that is usually the "developer" contributing to the project cost.
Everyone is focusing on the money, but this is really about the ability to bypass government control.
Which is why Disney was so insistent on bearing these costs in the first place.
Also, they have to do a determination on stay/go. Do they put more $$ into Florida or not? Is there a marketing risk operating there vs. not? Is there a business risk mucking about with theme parks or are they a 20th century phenomenon. Is expansion in the US the way to go or outside the US (Hard Rock Cafe voted for the latter a decade or more ago)? Which customer base has more disposable income that can be siphoned into the Mouse's pocket?
If their tax position changes, the financial benefit changes. Given the push for unionization that is occurring (Starbucks, Amazon), it might not be worth pissing around with lots of (formerly) cheap labour. If their bonds or bottom-line is significantly affected by such a change, they'll have to act quickly to avoid Netflix-like damage.
Or, all of this is BS, they hunker down and hope it passes in a year or two. However, it's been building up for 5-10 so far so that's probably naive. They can try funding the opposition, but that presupposes that there is a viable opposition in Florida. Disney Orlando requires tourism going to Florida to generate revenue, so they're damaged by stuff outside their control - people can get their mouse fix anywhere. And if the current Florida administration wins, the next round will be worse.
So, unless Disney really goes along with what's going down, they're in an unenviable position. Losing control of the marketing and ending up as Hillbilly Heaven would hurt them bad outside the US.
Part of the "magic" of Disney is that they get to control the experience from road maintenance to providing power to the park. Now that control will move to the counties with no guarantee that they will continue to provide that infrastructure to the same standard as Disney currently does.
This was a hedge done on purpose, so that (among other reasons) they wouldn't be 100% at the mercy of a single governing entity.
There's a loss of consistency between the two, but that's a feature, not a bug.
If one county doesn't cooperate with what's needed for, eg, a new park, Disney can threaten to put it in the other county instead.
At the least, aren’t there anti trust issues here? If other investors wanted to create a Disneyworld like park - they couldn’t.
At the very least they’d have to spend lots of time and money getting zoning approval.