So now you're *not* really going to finish it? Hmm. I'm not a developer myself but I would say, rather than upgrading the engine right now, if I were working on it I would try to get something done with what you have because you've done so much work in this engine. You can always upgrade down the line but imo (as an ignorant onlooker, yes) is that an upgrade right now isn't needed, especially when you can continue working on the HUGE amount of work that's already been done. Just my 2 cents though, take it or leave it if u want.
As I said I'm excited about this project but I understand it's a tricky business creating something of this magnitude, or of any magnitude really. So I wish you luck and hope you can find the motivation to keep plugging away on it. Anyway, I'll keep you updated on the videos or uploads as I make them. Cheers!