I would have to disagree on that. With all his experience I think he would be great in the front office. As a head coach he’s proven he can’t win without an elite QB. Most coaches need stability at QB to be successful. Belichick is too old and the NFL has changed. You need younger, energetic coaches that are more in tune with today’s game.
His people skills are reportedly dreadful. On top of that he's proven to not be a very good talent evaluator.
As far as not being able to win without an elite QB... Who can? A high percentile of coaches can't.
Young coach... Old coach. I don't think the "matter" is as great. It's more about "Can he coach?" and how good the front office is at evaluating and obtaining talent.
I think he can still coach. But his talent evaluation skills are not good.