For me, there are very few players or coaches that I become so enamored with that once they leave a team I like, that I follow them any more or care two cents about them. I didn't like Perk being traded but once he was, I could care less about him. Same with Ray or Tony or Posey or whoever. And it will be the same with Doc.
If he leaves, he leaves. I would hope that all this talk of how he has been away from family means he is leaving the team to take time off or go into broadcasting but if he decides to advance his career by going to a win now team, so be it. I think he hurts his Celtic legacy some by doing that but if he goes, he goes.