I guess I'll give my overall thoughts on the series.
The cartoon is the greatest cartoon I've ever seen. Even better than Batman: The Animated Series (Which was my favourite show until I saw Air Bender). Sad thing is, I never gave the show the chance until later on. I remember I was at an HMV and they made a "Book 1 Collector Edition". I remember I was looking at it but I was like "50 bucks?". The clerk that was on the floor was with me when I was looking at it, he paused and was like "It's worth it". I should have listened to him :(.
So while I was an app developer, my friend who I was working with, we were talking about it, since he watched it. So after I was let go, I was like "I'm gonna watch Air Bender and Young Justice". The first season was uneven, but holy hell the second and third season. I've never seen character development on that scale before. Not since Lost. As a testament to the show, even my dad was watching it with me. He also hates my nerd obsessions, so that's how good Air Bender was.
On to Korra. It was a good 12 episode mini series. The problem? It was a 58 episode order (vs 66 of Air bender) and had 12 episodes already used for first season/mini series. This left the show with uneven seasons. This severely hurt season 2. Season 3 though? It was every bit as good as Air Bender. Like, my jaw dropped, I was shocked with what they got away with and just how intense it was. Season 4, while I have yet to finish it (I think I'm 7 episodes in of the season), it didn't make me "want" to watch it. Though partially because I know the show will be over if I finish it. Though reading what happened in the last few episodes, I'll admit it does sound intense, but not quite as intense as season 3.
As far as this live action goes? Well, one thing the live action movie did well was demonstrate "bending". The live action movie more or less failed cause it was trying to condense 22 half hour episodes into a 1.5 hour movie (biggest reason). That approach was never going to work. Even a 12 episode retelling of the first season might be enough. Hopefully Michael and Bryan can remember what made Air Bender so great (I think they dropped the ball a bit with Korra).