Disney's biggest worry are world event's that lead to a downturn in the economy. That in turn hurts individuals discretionary spending. Disney parks is quite a bit bigger than Universal. In order to innovate, it costs them more money, but likely in a similar ratio. The nature of the business requires investment today, for returns 5+ years away. That is an eternity. No doubt they fear a world event, causing a tourism drought, with a few half completed projects in the hopper.
Honestly, they need Universal, they need skyplex, they need every little mom and pop attraction to continue to make the Orlando area, the go to spot for vacations. Despite growing pains that accompany growth, it affords opportunities. Airfare becomes cheaper, ground travel becomes cheaper. Food prices, lodging and many more industries all depend on this competition. There is an ebb and flow, and some times you are on the negative side of the equation. Industries grow at different rates. A nice new road in, isn't crowded at first, but eventually it fills to capacity, then people gripe about the road. There is a happy medium. Orlando hasn't found that happy medium yet.
I think Disney is smart enough to worry about growing too fast. Many complain that they drag their heals, and are slow to build. I won't dispute that. However, I think the institutional memory of the decline after 9/11 is still pretty strong. At their size, they must commit a lot of money to growth projects.
So when people discuss the phase 3 and 4 at DHS, and how it's already "budgeted", you have to look at it realistically.....a budget is a plan on a piece of paper(or maybe in excel). In a moments notice, things can change, the paper can be tossed in the trash, with everyone starting over. Anything can be moth balled if the situation is dire enough(Art of Animation). So you can budget for things, but it's another thing to actually have the money in that budget needed....and yet another to actually start writing checks.