I'm gonna pinch in my two cents here.
I feel like the game started out quite ambitiously, with the original roadmap and whatnot. Seeing this Act 1 drop like that, feels like they might be... giving up on the original plan, and simply deciding to just... settle for Bates as the final boss for Act 1, despite the fact, from what I remember, that Bates was originally supposed to be a mini boss within the game. Whatever the case, I feel like the Steam Release is not even remotely close to what the game should've been in its original official release. I can only hope they might decide to split the original roadmap into acts, if that's the model they want to pursue, but to simply stop at Bates, and then likely only having a smaller Act 2, would be a bitter pill to swallow. I don't want to be pessimistic, but I feel like that's where things are headed.