A Coach thinking he's going to be in his current job 20 plus years, probably fugging with whoever asked the question. (Some questions deserve ridicule. I mean it is Peter King.) Doesn't matter though, the BofA Miser wouldn't pay him anyway.
So if the path for College Coaches is spoiled and you don't like "Retreads" guess the only path is an NFL Coordinator job to NFL Head Coach.
It's definitely the path that's gotten the most jobs,
Eighteen of the league's current head coaches list their last job as NFL coordinators (10 defensive, 7 offensive, and 1 special teams). Two others were NFL position coaches, and you've got Trestman, whose last job was as a CFL coach but who has extensive experience as a pro offensive coordinator.
Of the seven retread coaches currently employed, four of them were coordinators before they got their first head coaching gig (3 defense, 1 offense) and two were position coaches. Coughlin was a college coach, but had coached at the pro level previously.
As of right now, five coaches were promoted from college jobs, but Carroll is an NFL retread and all but one (Chip Kelly) have previously coached in the NFL.
So yeah: This is where the majority of owners and GMs look for head coaches. It's not just the Panthers.