You can already hide objects depending on sub state...
I just wish for true scriptable behaviors, like what they seem to have done for the 2D UI. But this will not happen I think
Q3 had QVM's which worked a charm... it allowed you to take full control over the device context, game state and more, and you could really go beyond what most games allow us to do and that was 7 years ago. I still wonder why not many developrs have not picked that concept up.