Let's be 100% blunt and direct here. The reason he's not going Ren'py now is because of the time needed to learn it and master it as good as he did with RPGMaker over so many years and games.
It's cozy, it's safe, he knows it. Look at how he's recycling models, clearly all moms look the same.
He seems to be at a point where he's just doing it like a routine, to get the money. No risks, nothing new... 2 games at the same time, at least one will be good.
ICStor had a courage that few other devs have, tried to "live" of the existing patrons as much as he could, keeping them around with just a promise and man, did he deliver.
ICCreations is choosing the safe route at the moment. We all love his renders and games, but unfortunately we're not gonna see anything different from him, at least in 2018. Assuming he finishes these 2 games and has time to properly learn Ren'py, best prediction to see something new would be 2019.
PS: I loved his answer when he said other game engines have limitations and RPGm is much better for his style. This is a very diplomatic way of saying: I don't know how to use the other game engines and I'll do it in RPGMaker, which I already know. I'd be curious where RPGMaker bypasses the limitations of Unity or Ren'py.
In case you smiled when I mentioned Unity to a developer that doesn't move from RPG to Ren'py, then you might be a man of culture as well