Not sure there's any substance to all of this.
I tend to think that Doc comes back, with the understanding that he's going to miss a few practices (maybe take off a road trip or two). Lawrence Frank gets hired in Thibs role, handles some of the practices, handles the games while Doc's with his kids.
Don't think that arrangement would work for 29 teams in the league, but Doc is so well-established and respected with the Celtics core that I think this would be a good arrangement.
Del Negro; sounds like a wild-ass guess to me. If Doc *does* step away permanently, Jeff Van Gundy's the guy I'd like them to talk to.