Sorry to come late to this thread. I've been in surgery.
I think that BB has established a very clear line this year as far as what is expected of players on the team. Underperformers get benched, no matter how high their draft status (Butler) or previous pro bowl honors (Meriweather). Or they get cut (Burgess). Players who won't get with the program and put the team first aren't tolerated. Everyone is playing on the same page right now, from Brady down to guys like Danny Woodhead, Sergio Brown, Kyle Arrington, Rob Ninkovich and Brandon Deaderick. It's a great example of what can be accomplished when 53 guys are aligned in their purpose and understand what is expected of them.
With that in mind, I think that there are 2 ways to play it with Mankins:
1. Keep him as insurance. The OL has performed well overall, with the exception of the San Diego game. Sit him on the bench, keep him inactive, send him a message that he can't hold out and diss the organization and expect to come back and be a cornerstone again. Have him available for 9 games in case of insurance.
2. Play him. Extend an olive branch and make it clear that Mankins is welcome back - whether for 9 games or for the long term - as long as he is willing to get with the program and put the team first, play hard, and not be a distraction. If they can work things out with him long term, fine. If he wants to get with the program and play hard for the rest of the season and then move on, fine.
Personally, I'm hoping for option #2. The team could use Mankins. It would give us a lot of flexibility. A rotation of Mankins, Neal, Connolly and Koppen would keep the OL fresh, add insurance in case of injury, and allow some positional scheming. I think that the team's identity is sufficiently strong right now that Mankins wouldn't be a distraction. Guys like Brady, Branch, Faulk (still a captain) and Crumpler are too strong in the locker room to let things get out of control. And it's just possible that Mankins may come to realize that the grass isn't greener elsewhere.