Yeah, I just don't see how it is possible. 2023 is 6 years away which is a fairly typical (if not fast) build time for a theme park these days. Considering Universal would not just be building a theme park, but have to build more hotels, accommodate for parking, likely a second citywalk type area and figure out transportation between the two properties, I just don't see it possible sooner than 2023. None of this is accounting for any potential hiccups they may encounter along the way either.
Now they may WANT it sooner than 2023, but wanting something open and actually opening it are two completely different things.