Oh, and it's only an estimate if you're actually, you know, working, and you have a general idea how much work there remains to be done.
I thought that the May 23rd date (that he announced in March) is the one that he'll finally honor. Then he admitted he's lazy and didn't realize that he has to learn some software to actually render an animation that he got from fatcat. So when he said Summer 2020, I thought that the extra four months he gave himself would be enough to complete Part X, since he was able to put together an update within a month in the past, so he knows how much work it is and how much he still needs to do.
Right now I really doubt it's Kyle that's working on the game. He might have wrote everything up to Part VIII, may have conceived the Christmas prequel as something to release between Act I Part X and Act II Part I, so he had renders ready, story outlined and code to be written, but somebody actually may have robbed him of his Patreon and of his assets.