It's an interesting concept, not entirely original, but these days most premises aren't. I'd be interested in doing this, but my issue with it is the whole Korra being missing thing. I understand that it's part of the premise, but unless it's necessary to the overarching plot why have Korra go missing? If her being gone is not entirely necessary to how the story goes then there's really no need for her part in the story. That's just my professional opinion though.

My personal opinion on the matter though is that I think the story would be much better if it's not set in the world after the show rather in the between LOA and LOK. I was thinking along the lines of years after Aang died and Korra has either yet to have been found or still doing her training. Going at it this way we can do less work because we have an idea of how things are and how things are going to be in the world. There's also the matter of the chosen one's as a group, while I understand the reason for them why would it be necessary to make an an entire group when all that they would be doing is White Lotus jobs, but in secret ala LOA White Lotus and not mainstream LOK White Lotus. To be fair I do understand that if we go through the story this way there would be no airbendenders (BTW it tries to auto-correct airbender to bartender which is kind of funny to me), which does kind of suck and takes away the five man band element.

Anyway I apologize for the rant. but it was a horrible day and I needed to let off some steam. This is highly unprofessional of me and also rude. I apologize deeply and hope that this does not ruin anything for you. 

Hmmm I just realized that the chosen one's could also be called the Black Lotus, a sort of task force White Lotus master agents. They're main job is to look out for any threats to the balance of the world and maintain peace throughout the world, while (possibly) searing for the Avatar and protecting her from those who want to hurt her (Zaheer and his gang.).