It is what it sounds like.
Norm mentioned quite catagorically (I don't remember where) about Jake being on a 6 year tour of Pandora. A healthy rotation of scientific minds, workers and Sec ops personelle (well - those who survive) is to be expected. But a twenty million dollar avatar can't just be scrapped and recycled like the rest of the machinery. So here is the conflict: Grace put a full decade into her school, and will have been a resident at Hell's Gate for longer still. She's head of the avatar program, she has an excuse to be permanent staff. Dr Patel on his wiki page here is believed to be a member of the origional staff as well, and has not rotated back either. It is safe to assume that there are others whom we are not aware of, but we're still left with the problem of Jake's rotation (and probably Norm's too, judging by the way he says it, setting aside the rest of the program personelle) To create a biomechanical marvel with a life expectancy equivalent of the driver themselves at that price tag, only to be put down after 6 years seems to be a crippling waste of potential!
Am I just missing something here, or what? Do avatar pilots have the choice of staying beyond their contract (or some form of official extension thereof)? What becomes of 'disused avatars' if they dont? (not strictly thinking of Grace's, post-mortis)
What do people think?