I agree that the best thing to do is to keep going with Monica's Story. But if we talk about an hypothetical prequel, of course Monica's would be boring. But what about Victoria's ? Or maybe Philip's or Julia's ?I don't think a prequel could work. If he wants to stay consistent with the story in FB, Monica had very little sexual experience when the game started. What would that game contain ?
He could do a spin-off with her at the farm maybe, but I don't think that's allowed according with patreon rules, right?
And, to be honest, what do we really like about Monica? For me it's not her personality (more like a caricature than a real person) so if he created another world, with a good looking female MC, and an interesting personality, that would be a win for me.
And for spin-offs, I won't enumerate all the interesting possibilities, but I repeat, the most important is the current storyline imo ^^