One of the things about solo devving any game is that it takes an immense amount of inspiration. I can't imagine completely on my own coming up with new content art wise story wise and mechanics wise for a project as long running as this after a certain point, fact is as a creative at some point you just kinda run out of things you actually feel enough passion to work on if you are by yourself and have a bunch of baggage from previous installments. The fact he made in a very short amount of time comparatively and considering it was in between updates for this game that now abandoned side project I think confirms he's dealing with some SERIOUS burnout.
I think the best way forward even if it meant compromises in the art style or some buggy code would be to bring more people on I think he definitely gets writing help already so maybe putting some of his money towards commissioning art from elsewhere would be the solution. It reminds of Never Saint which the creator has dealt with so much of his own and collaborator's bs with their project the only way they could see themselves moving forward is just rebooting the whole game back to a demo in a different shell with most of the old content gone. This game is good enough consistently, especially bugwise, compared to a messy often half baked game like Never Saint so I don't think that reboot approach would make sense but if some of the scenes were drawn in a different art style and some of the coding was done by some newbie yeah it'd probably be out sooner and people would be happier. Maybe somebody like Scarlett Ann... their artstyle isn't so dissimilar from this game's at least for character proportions lol. That said I am uber biased, I love SA's other work. Either way though, maybe the answer is ask someone else to do the heavy lifting for a while.