I know I keep saying it, but any discussion of Bill which does not consistently distinguish between Bill the Coach and Bill the GM is utterly pointless. Keeping this distinction in mind doesn't immediately reveal the solution, of course, but it does clarify one's thinking as one seeks that solution.
In my mind, Bill the Coach is very much worth keeping, both for frankly emotional/fanboy reasons: He's our long-term, successful coach whom we are accustomed to rooting for and whom we would love to see reach his legacy goals; and for practical reasons: he is still an excellent game day and game scheme coach, worth keeping around purely on merit. He's our Coach, fercryin'outloud. As a GM, Bill is at this point a bust who absolutely must be gotten rid of if the team is to rebuild into a genuinely competitive group. Everybody by now understands why, right? I mean, we all saw the game yesterday.
Unfortunately, of course, the two guys - one of whom we'd like to see stay, the other of whom who has to go - are one in the same person. Given that theologians have been haggling over a triune God for centuries without reachins consensus, we are unlikely to unravel this conundrum any time soon. We have to decide. The word "decide" derives from the Latin to cut off or cut away. I guess this shows the ugliness of our situation. In any decision beyond the most obvious ones, in doing or having one thing, you forego doing or having the alternative. If you keep Bill the coach, you are forced to keep Bill the GM. If you ditch Bill the GM, you lose Bill the Coach. It's a genuine conundrum, a problem without a tidy or wholly satisfying resolution, hence the interminable squabbling about it. It's a Gordian Knot, and the only way to undo the knot is to do some painful cutting. Hopefully it's not a Judgment of Solomon deal.
This what I would do, what the Krafts should do, in my judgment, since this is obviously an owners-level decision. They have to offer Bill two and two only options: 1) You must give up any role beyond the conventional purely advisory input any head coach would have in the franchise's GM work. The extent to which the GM takes your input into account will be entirely at the discretion of the GM. Obviously, we will hire a GM wise enough to value your counsel, but the GM has the final say on GM responsibilities. You will remain as head coach. 2) If that is not acceptable, Bill, you've gotta go.
Obviously, the Krafts, whichever way Bill chooses to go, will make sure every face-saving and supportive gesture is made going forward. We will honor and celebrate what Bill has been, what he has given us, whichever option he chooses. But, to borrow a phrase, it is what it is, and it is not what it is not.