With the improvement in quality and effects on tv, i'm starting to think that maybe that could be the ideal place to tell Aang's story, you would need to tone down certain stuff, but you could pretty much follow what the original show did, with each Season having a set number of 20 something episodes featuring both, one-shot stories and the continuation of past arcs.
Having a set arc for 3 Seasons also helps, the only real problem would be the final battle with Ozai, you would need to tone it down a lot, but the overarching plot and world is quite adaptable. If it was a success, it could even open the possibility for more Seasons after 3 dealing with the remaining loose threads and the founding of Republic City.