cocos2dx supporting 3D scenes would be great!
One could have a 3D scene and cocod2dx for the game flow (helps, setting, etc) and HUD.
This could happen incrementally, for example, in one version we could have a basic CCLayer3D, CCCamera3D, CCModel3D, etc.
CCModel3D is the base class, from it we can have CCModelOBJ, CCModelCOLLADA, and so on. This makes easier to add support for other formats.
In further versions we could add bone animations, shaders, etc.