I happen to agree that there is a good chance that he will be gone. However, I don't think it's a slam dunk.
If the FO is intent on trading him, it is not helping their cause to shut him down for the season. Besides that, if Hanley can play first base decently, and I have strong doubts about that, then that solves a lot of problems. If he is completely healthy, it would be in the Red Sox best interest to let him play first base the rest of the way out.