Unless your next game will have some features that can't be done in Ren'Py, I think that's a bad idea. RenPy games are easily the best erotic games.
It does, specifically HTML5 support. Renpy can't do that, but Unity can. And Newgrounds is a massive market for porn games. But, if anything, it would be made in RPG Maker over Renpy. The movement and tileset is what I want from RPG Maker, but Unity has much more freedom over everything. But, this game would be quite expensive to make.
The plan is for a world that's somewhat open ended, not like a sandbox, but more like Pokemon. The plan is for it to involve management of multiple levels, from farms, food, people, and buildings. And of course there would be a brothel to keep people happy. This isn't a fully realized plan or anything, just a very rough idea. I can't really afford to be thinking about my next game at the moment, but I do need something planned for the future. My goal would be to announce a demo soon after HH is over.