That just is not going to happen anymore. Youth is dominating coaching now. Every coach wants to be a head coach at a big time program or in the NFL.
Coaching is a lot like the recruiting deal. If your head coach is dedicated to staying a life time, why would you stay, if you can upgrade your pay status.
Coaches leaving indicates that the head coach has made it clear he is staying for the long haul normally. The days of Bobby, Tom and JoPa are over guys. Who ever pays the best and has the best chance of winning is where they are going, see Urban Meyer or the dork at Alabama.
Money talks, bull $hit walks. Get used to it. College football is big business.