That's a fair point - with that logic they wouldn't have buillt the Animal Kingdom.
I just think that they could reasonably spend a billion dollars on the existing parks and we would still be wanting more.
Take a look at the DCA investment:
- Re-theme Orange Stinger into Silly Symphony Swings
- Re-theme Mulholland Madness into Goofy's Sky School
- Replace Golden Dreams with Little Mermaid
- Add theming to Paradise Pier
- Re-theme Sun Wheel into Mickey's Fun Wheel
- Replace Games on the Board Walk
- Re-theme Entrance plaza
- Add Red Car Trolleys
- Add Carsland, to feature 3 new attractions including Radiator Springs Racers
As far as I know, Toy Story Midway Mania and World of Color were not included in the 1.2 billion investment into California Adventure. The vast majority of that money seems to be for Carsland, with a huge portion of that investment in Radiator Springs Racers.
The issues with the Disney World parks aren't as extreme from a theming standpoint, bu they are from an attraction and dead space standpoint. The same amount of investment could certainly be spread across the WDW parks and accomplish quite a bit.
For Magic Kingdom, an additional E-Ticket (Tron) could be the only thing that the Magic Kingdom sees. Epcot could probably see the usage of existing infrastructure/attractions with a significant enhancement to 1 or 2 things (New Imagination Attraction for example).
This would bring them to the Animal Kingdom and Hollywood Studios. The Animal Kingdom is in need of the most work, but it would all start with a major expansion that would include multiple attractions. It doesn't have the theming issues like DCA so the money allocation can be largely devoted to new additions. Hollywood Studios is a bit trickier but could also use a significant expansion (Carsland or something else).
This might be a good hypothetical discussion for a future podcast or at the very least forum discussion, but if Disney were to allocate a billion dollars to the parks, I would divide the demand as such:
Animal Kingdom: $500 million
Hollywood Studios: $300 million
Epcot: $100 million
Magic Kingdom: $100 million
Now because it doesn't seem that this is in the cards right now, the equivalent of this type of mass investment will probably take place over a longer period of time than what's currently happening in DCA. I think that after the types of improvements that this would bring then it's far more realistic to talk about a 5th gate. Until then, I wouldn't count on it.