The dev's roadmap is to "complete" the Main storyline (Temple vs Tower). Should be two updates for that. Then one more update for aftermath/cleanup/fill-in. There might be some additional extras after that but the game editing software is reaching its limit so no promises. TBH I'd continue supporting PQ if all he did after that is update the character models that haven't been already, revise all the still images to use the latest models, fix older animations (a couple of older ones still have some clipping), etc. Lotta rendering time but worth it IMO.
Where any sequels might go is up in the air. I doubt visiting the Elven Realm, Qin, or anyplace really far away from the current area, but that's up to the dev and he ain't committed to nuthin' yet. That said I'm on board for whatever he does next.