They can't just up and leave.

What they can do, however, is phase out operations over time. They'd stop investing development money into the place and move towards more of a maintenance budget. Invest the development money that would go into WDW into their other parks. Close down existing attractions as they age rather than revamp them for the future as they currently do. Build new attractions in new locations, maybe even slowly build a new WDW piece by piece in a more friendly state. Start selling off their land in the area to buyers who would pay a premium for it while the parks are still there. There are plenty of ways to squeeze out profits without putting in the money they currently do to keep the place on the cutting edge.

In other words, it can't be done in a year or two but it could certainly be done over ten to fifteen, maybe twenty.