James Cameron's made a deal to make the two more Avatar films with Fox. The sequels will be released December 2014 and December 2015, and Cameron will make these self-contained films with original Avatar producer Jon Landau.
Said Cameron in a statement to the press:
In the second and third films, which will be self contained stories that also fulfill a greater story arc, we will not back off the throttle of AVATAR's visual and emotional horsepower, and will continue to explore its themes and characters, which touched the hearts of audiences in all cultures around the world.
So there you have it, another 4 years before audiences can return to Pandora and get depressed that they don't live on erotic aquamarine catman planet. Oh well, at least there's the Avatar nudie flick to tide you over.