Universal is doing two things: Spending billions on its current theme parks and buying land for its third and fourth theme parks.
Meanwhile, Universal's attendance figures go up each year; WDW's go down.
What is Disney doing? Waking up, slowly. Finally, after years of doing nothing, Disney is finally investing billions back into its current parks, some of them.
In a future not too far away, USO will have three or four theme parks - all with attendance figures reminiscent to those of WDW's glory age. WDW's attendance would have been abysmal had not Avatar and Star Wars saved it from complete disaster. In this scenario, forget a fifth gated park, EPCOT rarely stays open any longer.
How do we avoid such a dystopia? We avoid it by doing what Comcast-Universal are doing. Invest billions in all the theme parks, not just some, while preparing new gates for the future.
In the above-mentioned dystopia, USO is able to keep people on their property from venturing out to foreign Disney lands because they have everything in their three or four parks to keep everyone happy and monorails to keep them out of their cars.