The Charlotte Observer notes that Jerry Richardson has confirmed the four guys they're talking with - but that it's not over. That suggests at least one more candidate, orobably with a playoff team.
That most likely points to Eagles DC Sean McDermott, who would be an attractive possibility. The Eagles also occasionally allow promotions outside their own team for our OC job, and former MN head coach Brad Childress worked with McDermott for years.
It could also mean Jets OC Brian Schottenheimer, though the team has made it clear so far that defensive coordinators make great problem solvers (and it comes with a decree that the team will have a heavy hand in who hires the offensive coordinator and quarterbacks coaches), and that they'll value a strong defensive head coach/offensive coordinator duo.
Based on the team's criteria, high-value coordinators Mike Mularkey (Falcons) and Gregg Williams (Saints) are out because of their previous head coaching experience.
The Seahawks likely don't have anyone of interest, nor would the Colts. There's always the off chance that the Patriots do, but Bill Belichick wields so much power that it's hard to get a read on anyone who's good. Green Bay's Dom Capers has obviously been here already, but assistant head coach Winston Moss could be an outside possibility. Moss is a former player, and assistant head coach duties do somewhat prepare a coach for the head coach role.
As an aside, I don't know whether I like the extra power that the front office is wielding. I like that they're not going to let a coach dictate everything he's doing, but there's a balance. Hiring a coach and guiding him toward what you want is different from the more extreme - say, hiring a coordinator before a head coach, like Jerry Jones has, or meddling in the day to day ways of the team.
But, the team having apparently not put enough into what they felt they wanted in a coach is bizarre. If Fox was the best candidate but they wanted a more forward-thinking approach to the offense, they could've dictated that, either in 2002, 2007, or even without staff change. If Richardson didn't have the power to suggest what the team should do, or shouldn't do, on a yearly basis - why not?