Until something, anything, is actually proven, nothing should happen to Brown. He's a good football player. We know about the head issues. If he's willing to tune out the world and just play football he'll fit here. If not, and by that I mean if he's PROVEN that he isn't prepared to embrace the Patriot Way, he's gone.
One of the reasons this charade might actually work out is that we don't actually need AB. He's got no leverage and he knows it. He's GOT to make good or his career is practically done. Hopefully he understands that and is prepared to play ball and put the drama aside.
As for the various accusations floating around... even if I believe them (and to a point I actually do) Nothing should happen to anyone on the basis of an accusation. Accusation is not proof. When and if there's proof, then the team will act, just like it did with Aaron Hernandez. Right now the best possible action is not to act.