Ah... well, we don't live in the alternate reality where Disney will build something -- yet to even be announced -- in a couple of years... at least I don't think we do...
As an aside... when is "the 50th" technically set to start? It's in 2021... so are they going with Jan 2021 (start of the year... isn't this what they've done in the past?), or Oct 2021?
There was a previous celebration (can't remember which one) that started the October before the year started and ran through the whole year. For example, the 50th will start in October 2020 and run through December 2021.