Franklin had interviews lined up with the Browns and the Redskins that he bypassed to take the PSU job. Both of those NFL teams then hired substandard coaches. Franklin probably could have had either of those jobs. If he wanted to be in the NFL, he would already be in the NFL.
Contrast that to O'Brien, who had his agent leak the Penn State job offer to try and leverage it to land an NFL job. They pursued that for a couple of days, to land the Jacksonville spot for christ's sake, before finally "settling" for the Penn State offer.
Franklin is a PA guy, dreamed of playing for Penn State when he was in high school, and can make all the money he needs and have all the security he wants at Penn State. He's building something for the long haul. No guarantee about anything in this life, but he isn't a guy who is lusting after the NFL. There are college guys, like Urban Meyer, who want to coach in college. I think Franklin is one of those guys.