Well if its anything like the others you will fight ether him are osira last hard to say tho
Doubtful, he always goes with the hinted at, subtlety mentioned but relatively unknown villain behind the scenes. Crayden will be dealt with and then you'll probably have 1 or 2 more big bads to address like the snake god who's likely controlling Laquadia, the Dragons of the nine, the Ahn'Terra, or whoever Zweibelle really works for. Or even still a completely unknown as of yet threat, lotta options there, I just very much doubt Crayden will be the final boss.
Anyways that is likely a long, long, way off....., this developer will drag the development out as long as possible to keep the monthly payments coming in afterall. For reference remember his last game, while the scale of it was not quite as large it was similar to this & Gabe made it in far less time with far less resources, as well as being less adept in RPGMaker at the time. Bottom line, he would have done the same again with this game but then... Patreon became a thing, a whore of a thing too good to pass up.
The whole state of the game is actually pretty amusing, the massive misappropriation of funds in particular, on shit no one ever asked for or wanted(busted ass eurotrash cosplay girls, TONS of commissioned art that's not even going to be used in-game ever, lame ass mini-games like strip poker, etc etc)
And then there's the polls where he asked supporters for input on what they wanted most, which was more focus on the MC getting laid, only to turn around and do the exact opposite time and again. LoL.
The man is so consumed by his own fetishes he just can't seem to bring himself to fulfill his promises to his fans/supports. And yet he's still getting paid, like I said, this shit is amusing.