In long, noooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo.
That said, if one had to do a sequel to Avatar- and in the off chance a studio exec actually trolls the Escapist forums, I offer this idea freely and without expectation of compensation for use by anyone who can- I'd suggest you keep the humans out of the picture entirely. Or at least, the humans still tied to Earth, as opposed to the ones who've "gone native." Any sort of "We need to band together again to keep the greedy humans from butchering our sacred planet" is going to be just that, an again. It will be a very pretty "again", no doubt, but Avatar itself is pretty much a retreading of old ground, and there's no question about it. Go the same route again, and you're asking for an apathetic response.
It would be much better, to my mind, and much more interesting to deal with the implications of the human technology that remains on Pandora. If the Na'vi splintered on the basis of those who embraced the wonders of the humans' science versus the ones who cling to the old ways, you could create some very interesting conflicts- conflicts that offered a lot more shades of gray, at that.
