I kinda feel like Doc's time has come and gone. I *like* Doc as a coach, he's not outstanding but I think he's better than most and will likely have success when he coaches again.
But, head coaches have a shelf life. There's a specific reason Larry Legend stepped down after three seasons in Indiana; players start to tune you out. Seems to me that Doc's having more and more trouble getting guys to exert themselvses on a consistent basis. I blame the players for this - but it's a lot easier to bring in a new voice than to trade all the players.
What I *don't* want to happen, assuming the core of the team stays more-or-less intact, is for them to bring in a rookie head coach - Tom Thibs or anyone else. Not sure this group would respond well to someone brand new and feeling their way into coaching. Gotta be someone veteran, someone who'll preach defense, and someone that's respected but known for not being a pushover. Obvious candidate would be Larry Brown, if he prys himself away from Charlotte, or maybe Jeff Van Gundy (I'm a Van Gundy fan, at least for Jeff).
EDIT: I should say, too, that I really like Doc. When he says something like this:
"The one [thing] I will say is I'm committed to Boston," Rivers said. "It's either stay with the Celtics or I decide I need to stay more with the family."
... I believe him. If he steps down, I do believe he'll be a head coach again in due time. He'll go back to broadcasting games on TNT, maybe on a part-time basis. But, he's shown himself to be a pretty good coach over the years, those crappy young teams always played hard, and not every coach could have gotten everyone to buy in as fully to the ubuntu concepts two years' ago. He's a good coach.