I dunno about him "following through." After all, following through would mean an actual update, not just saying that you're not giving up the ghost. And the dev has a financial incentive to not admit that for as long as possible.
And putting up a few slides of previews, even if they do require purchasing new assets, seems like a pretty trivial way to keep things going.
Frankly, the thing that's always stood out to me as odd about this whole affair is the idea that they were remaking the game in a new engine, and... just not releasing it. Like, why wouldn't you release the old chapters as they were completed? Surely, this switch is going to require new saves anyway, so why not let people get their progress back to the cliffhanger while you work on this nominally enormous update?
To be clear, I don't think the dev is actually trying to scam people. If anything, I'd wager the issues are a partly trouble learning new tools mid project, but mostly a mixture of ambitions far outstripping capability, and a pressure to have a more substantial update due to the time between releases. But like I said, they're not capable of delivering what they want to, so they need more time, and then more time passes, so the update needs to be even bigger, but uh-oh, can't deliver on that either, so now even more time is needed, which means an even bigger update, and OH, GOD! It's an ouroboros of failure and self-sabotage!
That said, I also can't fault anyone, especially people paying them, if they feel scammed at this point. It's easier for me to just see incompetency here, because I didn't give the dev money. If I was a monthly subscriber hearing the same song and dance over and over and getting a few slides here and there, I'd probably feel differently when my goodwill was finally sapped.
