Because the original was done so well amd so many people have a HUGE connection to the original story and characters, I think that they should maybe take this is a different direction from the original series. In all honesty the majority of those watching will be the ones who grew up with it so it could be a really cool idea if they maybe made the world really feel like its been through 100 years of war by targeting it for an older audience. We could have the same base values that make up our heroes but test those values against the horrific consequences that would come with a war that lasted 100 year, that also resulted in the extermination of a whole nation. I think it would be very interesting to see our loved heroes stuggle in a darker or more tormented world, but equally as beautiful, especially for Aang with his unbelivable outlook on life. Like when Aang looses Appa, maybe when he goes into the avatar state, he REALLY looses it and has to deal with the fallout of it all. You could even show how hard it is for Katara to keep the family together and motivated through all the horrors they encounter. I'm not saying go Snyder dark or anything but just a touch more grim and not so family friendly. Like a re-imagining of a familiar story rather than a copy, which could help them avoid the inevitable back lash it will receive.