I'm going to talk over my full plans soon~ish (next month if we still haven't had any updates) for the future of this project, but sadly, continuation isn't in the cards. I will (at least) conclude the game, but there are many reasons I'm not continuing this project without Ferdafs. For now I'll just hit the two main points here.
The primary reason I'm done when Ferdafs stops (and after I've put an ending on it) is that it just isn't something I really have a lot of interest in doing. Converting assets and script from one game to another is fun, and while it isn't "fast" the time requirement is far less than making those assets from scratch.
Going into full development mode for a game is a full time job, not a fun hobby. I already have a job and I enjoy what I do. It's flexible enough to let me take on fun projects like this one, and makes me enough income that I don't need to charge for my time on things like this. Full time development is FAR less flexible (I'd be on it 10 hours a day 7 days a week), and my income would be based on people donating (rather than charging for my time).
The second reason is art. Look, I'm not a good artist, I'm just not. I can edit, I can trace, I can reuse stuff, but I can't really make new things; a major requirement for, you know, making new art and adding it to the game. The ending is already going to stress my limited ability far more than I would like, continuing is just too far beyond my skill set. Even with a full time artist (which, I don't have), it is still a massive amount of work and time on my end (planning, writing, coordinating, implementing, testing, revision...ing).
Additionally, if I was going to keep creating, I'd choose my own story/game. Then at least I'd feel a lot less bad about monetizing it (to be clear, no plans to do my own game at the moment).
All that being said, while promising the distant future is always an iffy bet, if the Unity game just goes on a long hiatus, I would have interest in resuming my work on it in the future. Who knows what the actual case would be. No idea what future me is going to want, but at the moment it is something I would do.
As to someone else continuing the renpy project, I'm mostly indifferent. If someone want's to make a mod of my mod, go for it, I certainly did. Heck, they don't even need my permission! I'd suggest giving it a different title, and don't be a dick and claim all the works as their own and put it behind a paywall or something, but outside of that, sure, whatever.
The assets are all there in the release, so it's free for anyone to modify and improve on. They don't even need any special tools, the code is just plain text (lots of people already make changes to it in their copies of the game), art is just pngs (for the uncompressed files), nothing really special or encrypted of anything.
Lastly, while I am stopping if Ferdafs does, the "when" I stop is less... defined. The conclusion won't be a fast thing, I expect it to be months of work spread over several releases, but again, I'll talk more details next month if still no update from Ferdafs.