The idea of taking away someone's bending coming from Aang and Ozai's fight makes a lot of sense to me, frankly. It seems sort of resonant? We've seen some of the other innovations of Aang and co. being way more commonplace in this modern society. Metalbending was Toph's invention, but there are lots of them in Republic City, and lightning seems to be a common part of firebending whereas Zuko didn't know about it IIRC and Iroh was pretty clear that not everyone could do it. I guess if bloodbending shows up as a relatively commonplace medical tool we'll know for sure? And it would all fit pretty well with the stuff we've seen about how bending and modernity are pretty great, but can be turned to worse ends: metalbending is cool, but the police state that uses it a LOT seems not entirely positive and any random criminal being able to lightningbend seems worrying.