[quote=@Gisk]
If we go a whole Avatar cycle after Korra, it would be an Earth Kingdom Avatar, and it would likely be something close to a modern setting.  This also means we don't have to worry about stepping on the toes of canon.

This also means we have airbenders again, and members of any nation could reasonably exist on any side of a conflict we'd have. 
[/quote]

That's a fair point. We even have evolved organisations in specialized bending, such as Metal Benders, Lightning Benders, Spirit Gurus (air benders), and even things like Chi Blockers.