Meh, currently I develop the game using 3.4.9. It's last stable version and version that can work with CocosBuilder. But I can't say that cocos2d brilliant, it has bugs, problems and awkward things. So, it's just more less stable and u can develop games using it...
Also, no support, no updates.. ehh.. brilliant
@slembcke said, that you just received money from Apportable and didn't actually work on cocos2d code. This can be easily checked by activity on github. So, about what your development you are talking about? A rhetorical question.
You are saying goodbye for a couple of people here, thats so ironically, but bye bye anyway
I think this can be cocos2d-swift. However, you should realise that engine core must be not based on Apple features, like app thinning or any other. Also, it' should have a good editor, like was CocosBuilder and must be cross-platform. Without all these it's just waste of your time.
All this can't be fun and good. I'm writing as is, thats true. Just try to accept and realize it finally.