This is what we, as Natives, know will happen to the Na'vi. They may have been successful in routing the humans but we know the Earthlings will be back with a massive army prepared to use any means to secure the mining of unobtainium. The army will be trailed by the social scientists, the teachers, the religious cadre all of whom will feel an obligation to save the Na'vi from themselves, for the greater glory of God and for profit, whatever form it may take.
This is what we expect James Cameron will address in the sequel to Avatar and that is why we cringe when we see the movie.
Since the Na'vi are (or should be) immune to human disease and since they defeated the humans, the sequel won't be exactly as George-Kanentiio describes. I'll go out on a limb and predict it'll be totally different.
I suspect it won't include another human invasion, or humans at all. Rather, Jake and Neytiri will be rebuilding their clan's society when a Pandoran threat arises. For instance, the red-skinned dog people will attack the blue-skinned cat people. They'll capture Neytiri and Jake will have to go on a quest to save her. Or Jake and Neytiri will have to journey together to find a sacred doohickey to protect them from the enemy. The movie will end with Neytiri revealing she's pregnant with Jake's baby--because James Cameron seems to like predictable stories.
For more on the subject, see Army vs. Indians in Avatar and Evoking Natives in Avatar.