I think the situation used to be that Disney and Universal were in a semi-mutually beneficial relationship. That is, Disney has, for decades, provided a good enough reason for families to book a 4-7 day vacation in the Orlando area. Universal, and to a lesser extent, Sea World, have served to offer an attractive theme park alternative for 1 or 2 days of a mostly-Disney 5 day Orlando stay, especially for families who had already seen all 4 of Disney's main park offerings. This was especially true during the Great Recession, where Disney essentially froze their building altogether while Universal spent millions on the two Harry Potter expansions. This resulted in a massive increase in Islands of Adventure's attendance (and later Universal Studios') but also a nearly-identical increase in attendance at Disney's parks that were offering nothing new, suggesting that Disney was piggybacking off of Universal's efforts. After all, the two Universal parks are hardly enough to justify a family spending a full 4-7 days to see, especially when you factor in the cost of airfare. The model, as before, would be that a family would be coming to Orlando in order to see the Universal parks, but still would be spending a majority of their time, and quite possibly their resort stay, with Disney. People sometimes ask- why didn't Disney build anything during the late-2000s to justify families making return trips to Orlando? Because Universal was doing it for them.
Now, everything has changed, because Universal's waterpark changes the entire paradigm. Now, Universal will have enough park and waterpark offerings to constitute an entire 4-day stay, or at least enough days of a vacation to justify families using their on-site resorts, cutting Disney out of the picture altogether. This is why, more than ever, Disney is going to be motivated to not just match Universal's offerings, but diffuse to some extent the allure of their attractions. If Disney and Universal were not true competitors before, they're about to become such.
of course that was different and one wanted to be ahead of the other. And now, Disney and Universal often have imagineers bounce between the two. Of course concepts are taken and revamped and are similar. It's still not the competition some want it to be.
