Many outside of Disney believe that's exactly what they plan on doing; especially down the road(both Universal and SeaWorld). Where I stand, which is more on the SeaWorld side of things, they fully expect Disney to come out with something about Avatar. So much so, that they have been getting a ton more Empire of the Penguins goodies ready for fans. There is a big blitz coming from them in the not to distant future. They are determined to not be overshadowed by Transformers.
Now like I said, Im seeing it from SeaWorld's POV. But as far as everything Ive been told, which has been all year, Avatar has been chugging forward full steam. They apparently got most, if not all, the survey work done and are just getting the logistics of building down on paper. Either that or they have SeaWorld and Universal completely fooled. Cause SeaWorld has been having tons of meetings recently about if they should delay their next big thing till 2017 to avoid competing with Pandora. Which is a big deal, since the year delay will probably cost SWO a nice chunk of change. Not that the whole thing wont already, but still.