While a sequel is planned, we aren't sure what it is going to be about. There have been some possibilities about the sequel. It is certain that they keep following jake and neytiri but it isn't sure that they will stay on pandora, they could also explore other moons in the solar system alpha centauri A. There could also be a ressurection of col. Quaritch who might be cloned. Selfridge could also return in the next sequel but we aren't sure if those will be memories or that they'll actually return. It will also feature the oceans of Pandora.