First, the fun, living in Fantasyland approach. Yes, a 5th gate would be awesome! And the 5th gate I would want: DisneySea.
Most sites I visit that have ranked all the Disney Parks put Tokyo DisneySea at number one on their list or in the top two or three. Japan and Tokyo Disney Resort are on my bucket list and there is a good chance I'll get to put a check in that box sometime over the next decade. It won't be cheap. I will feel very blessed/fortunate for my wife and I to accomplish this.
The average family has a tough enough time making it to Walt Disney World every five years (if at all) and the odds of the average US family getting to Tokyo, probably close to nil. I find myself a little irked that the Imagineers of our beloved US company came up with these fascinating plans, and are they here in the US? No, they are in Japan, and it's the one resort that Disney doesn't own a piece of (they get licensing fees from the Oriental Land Co) Nothing against Japan, they kicked butt in the 80’s and could afford to throw money at whatever they wanted. And they threw a lot at Disney.
I would like to visit that park many, many times, but will be joyous to get there once. Not looking for an exact replica, but something close. Tower of Terror is already in DHS, so something different there. A park that is something close to the original.
I want DisneySea in Florida.
Now secondly, the reality of a 5th gate. Is it possible in the next few decades? Sure. Is it likely? Err, very, very low odds on that. Disney is a business. They have found a way to dominate the box office, not just here but around the globe. I like to visit Box Office Mojo regularly and look at the worldwide totals for movies. Disney has done extremely well over the last decade in film. How? They buy things. Everybody's favorite on these forums favorite two letters: IP. In business, it works.
Disney reels you in with the flat screen. Then they make these awesome promo videos enticing you to visit one of their resorts to see their IP in person. China and India, two countries with over a billion and a growing middle classes, Disney wants more resorts in these regions to start getting more money out of their wallets. I'm sure these take precedence over a 5th gate. Florida doesn't have many problems attracting people. Disney once even had plans on the board for Disney Wharf in Sydney, Australia (a country of 25 million). All that to say, Disney wants to dominate the globe with their Resorts. Easier to get a middle class Indian to Mumbai or Chennai than to Orlando.
Also, Florida parks need a lot more work done to them. Magic Kingdom had almost 21 million visitors last year. Epcot, AK & DHS were all between 11 and 14 million visitors each. My hunch is their goal is to get these numbers balanced upwards for the latter three parks. After the 50th for MK, you'll see a lot more attention given to those three. We are already seeing that for Epcot. Their 40th is just around the corner and you know the 50th will be big, AK turns 25 in 2023 and that will be a big anniversary. I'm guessing a lot love shown to that park at this years D23 or definitely 2021 D23. DHS is my least favorite laid out park, it needs better flow. Everyone is going to congregate in the back corner with GE & TSL. I've heard Jim Hill mention there are plans to work on the other side of the park: possibly a Monsters Inc Land and the park having a circular flow for guests?
All those things are going to take a lot of money. And I'm sure we are going to see a lot more resorts/DVC added too. Shanghai Disneyland cost Disney 5.5 billion and I don't know if that counts what China put in. If GE cost a billion, and supposedly that is a low estimate, a brand new DisneySea in today's money would probably be at least 7 to 10 billion dollars. You could do a Villans park, maybe 3 to 4 billion, but remember how horribly California Adventure was received when that was done on the cheap.
As much as I would love DisneySea in my backyard, I don't see it happening for a long, long time. There are way too many others places for Disney to invest their dollars. Thanks for reading my book of a post!