Sup all, just putting my word out there, hoping someway this might spark an idea,
I have always seen the avatar world apart of the Ying / Yang concept therefore always needing a balance, if there is always a need for a balance then who is to be Aang's oppisit? who is Aangs' Yang to his Ying? therefore allowing a new enemy arrise who is bent on domination, and not to bring balance.
Also the air temple monks were always the most spiritual, i would like to see a story line, where they managed to cross over to the spirit world, and guide Aang to defeat a the new enemy.
Catch
Dane.