It is interesting you mentioned this. Tonight I was having this exact conversation about this with my neighbor, an Auburn grad.
My neighbor made a good point. Franklin has it made at Vanderbilt, he looks like a rock star, has the program going in the right direction and has job security forever. You have to give credit to Franklin, he has played the schedule he had better than any other Vandy coach in recent memory. No doubt that was helped by Auburn and UT being WAY down with Mizzou playing without their star QB.
On the other hand it is a balancing test. Franklin can stay at Vandy for as long as he wants and be a legend, or he can risk it all and actually have the resources and the talent to be expected to beat the big boys by going to a school like Arkansas. My wager is that Franklin stays for a few more years, tries to build a better resume and leverage that success for a huge gig somewhere. That has a massive downside though, with so many SEC coaching changes. A couple programs are poised to make massive upgrades: it will be up to Franklin to prove if he is really this good, or if he is just being benefited by the teams he has played being way down.
For those that think a top 15 recruiting class is stellar, it is. But it isn't NSD yet. Even if he gets a top 15 class, his talent level when averaged with the previous three classes will still be near the bottom of the SEC meaning continued drastic improvement is unlikely.