The Justice Department is approaching crisis point, at the top levels. This is chess maneuvering and manipulation, I cannot see all the angles, nor do I even think it is possible for the people involved to. If Brand leaves, that puts the #4 person up next, I don't think career DOJ people will back Trump's agenda, the way he wants.
They see the legal implications, and more so, perhaps, the moral ones....Most of these people don't spend their lives believing in law enforcement and honor, and duty, only to sell out to a Hollywood/Manhattan sleaze bag like Trump. These people have really SEEN things in the line of duty, the whole world of reality tv and money, and fame is not aligned with how they see the world.
I don't believe can just appoint a white trash talk show host insurance saleseman from Iowa to the job.
And sooner or later, Session's is going to have to decide where he truly stands, with the Department of Justice, or with Trump, because they have rapidly conflicting paths.