yah he's supposed to do that before avatar but he decided to wait, he wants to make her full CGI and not be able to tell if she's a actor or animation apparently. So he's waiting for the tech to catch up for cgi.
What we have here is a 'sliding timeline'. This version is the opposite of the one Marvel uses, where everything happened 'X years ago', regardless of what year it is now. This version is 'X years from now'.
Isn't it kinda... heart-warming that Neytiri would push him around in that wheelchair for him? The same kind of feeling I hope some or most got when she knew about the system that plugs them into their avatars, and she got the breather for Jake and everything.
... Bleh, I'm being too soft on a movie that's Pocahontas 2.0.