If Randy Shannon is indeed the hire at defensive coordinator, it won't address a constant problem that we've had at this coordinator position under Mack's reign: turnover. With the constancy of that turnover accelerating since 2003.
Reese, Robinson, Akina/MacDuff, Chizik, Muschamp. The last four over seven years.
All from completely different coaching traditions.
Randy Shannon will be a head coach again. This would be a 1-3 year hire. We'd be looking for another defensive coordinator soon.
Mack Brown can't personally cultivate a coordinator replacement from an Xs and Os perspective as a Nick Saban or Butch Davis can. For that matter, he can't cultivate an offensive coordinator either. That's a systemic program disadvantage if you want to guarantee constancy in the face of turnover. That's why Boise still remains Boise, even when they lose their latest hotshot. That's why Alabama will play good defense post-Kirby Smart. Their head men are grooming future coordinators in every meeting and hiring position coaches with coordinatorship in mind.
That means we either accept it and continue to play the short-term game like Keynesians, accepting that in the long term we're all dead, or we make hires in position coaching with the understanding that they must have upside as potential coordinators that the new DC can and must mentor. Same goes for offense now that Greg Davis has departed. If we don't ever have the opportunity for a homegrown solution, we'll be playing this game every two years.
The other option is to go a different direction from Randy Shannon altogether and try to identify a young gun without the requisite skins on the wall for a near-term head coaching job, but the solution, at some point, needs to come from within.
Something to consider.