Without sounding like I have no faith, I will say that I don't believe Disney could pull off an Avatar ride in a way that would live up to the potential and depth of the Pandora that James Cameron spent so much time crafting. In the same way that I didn't believe Disney could (or would) put enough focus on Harry Potter, I don't believe Disney would give Avatar its due if it were to acquire the rights to the franchise for use within the parks. If there is any company I could see this one being pulled off in, it would be Universal at this point. And truthfully, I can't imagine any company pursuing a full-blown attraction based on Avatar besides a 3-D film (probably one to replace the incredible, but slowly aging T2:3D) because the amount of detail that would be expected for a faithful recreation is just beyond reasonable range (in my opinion) for any company interested in such an endeavor.
I loved Avatar and have seen it twice in IMAX 3-D, so I can't say my opinion isn't skewed, but I will say that for the reaction this film has received, any company considering to take on the franchise would have to do something major to integrate such a rich canon into the theme park world.