I would be really surprised if they keep Joe Johnson throughout the season. It seems like it is kind of unpleasant for both sides if he does. He is 35 years old and probably has a max of two seasons left playing. Why not let him go to a team that at least has a chance of making some noise in the playoffs. While I realize his contract is a monstrosity, it is expiring and the further it gets in the season, the less expensive it is.
His presence on the roster also decreases the amount of minutes available for their really only legit prospect in RHJ. If they could even get a change of scenery young guy and another expiring for him, that would be a good trade. Failing that, they would probably buy him out. Let us remember that this is not a KG in minnesota situation where he has played their for close to 10 years and wants to own a state in the franchise upon retirement. Johnson is the consummate professional so I can't ever picture him demanding a trade but he is from Arkansas, went to school in Arkansas and has no ties that I can think of to Brooklyn. If anything him, going back to Atlanta makes some sense.