In the 25 years between Bryant and Saban, the average tenure of a Bama head football coach was 3.57 year and that's not including Mike Price and Joe Kines. I think it worked out okay for them. No reason it can't work out for the Vols.
You're right there is no reason it can't work out but let's look at the coaches and situations in that 25 years (minus Price and Kines)
Ray Perkins (83-86)
Reason for leaving: Accepted Head Coaching job for the Tampa Bay Buccaneers
Bill Curry (87-89)
Reason for leaving: Accepted Head Coaching job at Univ. of Ky. after contract dispute with Alabama
Gene Stallings (90-96)
Reason for leaving: Resigned at the end of 1996. Alabama was about to get the hammer dropped on them due to violations during Stallings' tenure
Mike DuBose (97-00)
Reason for leaving: Fired after 2000 season. Finished 11-3 in 1999. Pre-Season Ranked #3 in 2000 and finished the season at 3-8.
Dennis Franchione (01-02)
Reason for leaving: Accepted Head Coaching job at Texas A&M
Mike Shula (03-06)
Reason for leaving: Fired after 2006 Season. Finished 10-2 in 2005. Expectation was 8-10 wins in 2006 but finished.
The only two firings during the 25 year gap between the Bear and Saban. Both of the firings came after seasons where there were med-high expectations and sharp declines in records. Dubose went from 11-3 to 3-8 in a season with National Title expectations, someone could easily look at that and see why he got the axe. Shula went from 10-2 to 6-6 in a season where they had decent expectations but some could also see why he got the axe. Outside looking in one could see the declines and why they were fired. I would have classified the Bama job as Low-Med Risk. There are expectations at the university (so a coach will have to meet higher expectations) but if they fire somebody it will be due to a sharp decline in performance.
Let's say Nebraska beats us in any fashion and our record is 8-5. The expectations were high this year and there was a 1 game decline, okay it happens. The program is running clean with little to no player issues (arrests), our academics are doing very well, we have the #1 recruit by some services committed for next year and oh yeah he turned a dumpster fire into a Top 25 program (remember we are ranked #21 in the CFP Poll).
And we can him because he didn't meet expectations in one year, a mild decline in record and he may not be the best in press conferences. This right here is the definition of
High Risk because yeah you can do well, build us up and build up expectations but if you have one year where you don't meet the expectations and there is a slight decline you might as well hit the road jack! This job will come with zero security attached and be a rotten looking egg to any decent coach.
I'm not saying there's no reason it couldn't work out but probability will not be on the side of success if Jones is fired right now.