Considering how Korra ruined the franchise, I'm just going to assume the current state of this Avatar world is not going have any of the blame directed towards her. Viewers with brains will know that in reality it should be her fault, but the story won't touch upon it.

The premise will most likely be that a nuclear war or some shit, thanks to the non-benders, caused the world to become like this and girlboss Avatar Korra couldn't do anything about it. The even-darker-skinned disabled girl with god-like powers will need to rebuild humanity.