I'm anti-Sean as head coach (I'd like the replacement to be a little more well traveled to help cultivate a larger network), but let's say that Del retired at the end of this year, Rhoads got fired, and we brought Mangino in to be OC/AHC to help prop him up, then I'd be more okay with it.
That said, if Bill walks out that door, and Hayes goes with him, I'd be curious to see who Sean would promote or find as the DC.