Back in the good ole' days, before I watched football, NFL headcoaches presided over one team like Tom Landry with the Cowboys, Chuck Noll with the Steelers, Don Shula with the Dolphins, and Bill Walsh with the 49ers. They may have coached elsewhere, but that was mostly wiped from the collective conciousness and can only be found at Wikipedia. I'm sure there was coaching turnover much in the same where there is today, but I don't recollect Super Bowl winning coaches testing the free market the way they do today. It probably stems from the four aforementioned coaches winning a majority of the Super Bowls.
In 1995 Jimmy Johnson went to coach for the Dolphins and the big story of the time was, No Super Bowl Winning headcoach has ever won with two different franchises. Oddly enough, that is an anomolie which has held to form. Parcells and Holmgren came close, but it still remains true.
Presently in the market, with many of them itching to return to the sidelines are Holmgren, Gruden, Shannahan, and Billick. Dungy appears to be happy with his semi-retired status, so I won't consider him.
I will throw this out, cliche's don't become cliche's if there isn't some truth to the matter. I think owners would be wary to hire any of the 4 coaches (Gruden and Billick because they were offensive geniuses who relied on defense to win a Super Bowl, and Holmgren and Shannahan because they have proven that as GM's and player talent evaluators they are questionable at best.)
With teams fighting hand over fist to throw money at these coaches, maybe owners should open up a history book.