I really don't think contract negotiations should influence selection. I dread to think that the Wallabies persisted with Cooper at 10 just to get him to sign a 1 year deal. He never did enough to justify his selection IMHO.
Even if one of the backrowers decides to leave, I cannot think that any of them would not put in 100% effort regardless - it would be insulting to them to think otherwise. As for combinations for the following season, there will be ample time to establish those.