After watching Avatar a couple of times, I somehow noticed some things that gave me an idea that the Air Benders are not yet extinct but are in hiding. So far I have only 3 evidences:
- In the episode "The Swamp", a huge tornado suddenly appeared leading the Avatar and his gang to fall into the swamp. The origin of the tornado was not very clear, but I think that an air bender "guided" Aang into the swamp because what else can create a tornado out of nowhere, in a forest, surrounded by mountains.
- In the episode "Bitter Work", while lecturing Zuko on how to redirect lightning, Iroh mentioned that Air Benders have a great sense of humor. The questions is how can Iroh know something like that when the Air Monks went extinct 100 years ago when Iroh is 64 years old, and he have not yet converse with Aang, I think that the White Lotus is hiding the descendants of the Air Monks in a very safe and unknown place.
3. The lack of corpses. While watching the whole series only one temple had a corpse in it, only the Southern Air Temple with Monk Gyato's corpse, you maybe thinking maybe the Fire Nation soldiers cleaned it, I think not because if they even bothered to clean up the dead bodies, they would even have bother to clean up Monk Gyato's. I don't know about the Eastern air Temple because Guru Pathik might have cleaned it. Also if watch the scene where Monk Gyatso died, not only his skeleton is there but also other soldiers. With this I suggest that Monk Gyatso sacrificed himself to buy time for others to escape and there is another air bending technique that is deadly because the soldier's corpse where to far to even strike Monk Gyatso, maybe controlling oxygen perhaps therefore killing himself?
So far I have only three evidences that proves that Air Benders are still alive, but with the upcoming spin-off of the Avatar, this theory of mine might just have a chance, and as a reminder this is just a theory, a poor, helpless fruit of my imagination and too much coffee.