Let's not get overly optimistic.
Could 2022 happen? Sure. But it's not a likelihood. You have to remember, this is an entire new resort with a new park, citywalk, hotels, etc all being built on land that needs to be cleaned up first. They also are going to want to carefully plan out how they build out this first phase so it leaves them in a great position for a Second water park, more hotels and a potential fourth theme park far down the line.
This isn't something you rush.