Dynasties do not come with expiration dates. The end is always apparent in retrospect, once the college football historians perform their autopsies. But in the moment, when the team appears as if it will be good forever, it can be difficult to detect the malady that will bring its life on top to a close.

So how will we know when Alabama has peaked? The No. 2 Crimson Tide, who will play No. 3 Michigan State in the Goodyear Cotton Bowl on New Year's Eve, are the only team to repeat in the four-team College Football Playoff. That is only the newest bauble on Nick Saban's charm bracelet.

Alabama has gone 96-12 over the past eight seasons. That's an average of 12 wins and 1.5 losses. In that time, the Crimson Tide have won three national championships. Alabama is only the second team to reach No. 1 in the AP poll in seven consecutive years (Miami did it from 1986 to 1992). Alas, Alabama has risen only to No. 2 in 2015. It will take another national title to keep that streak alive.

That is hardly a sign of demise. The Tide just became the first repeat champion in the SEC in 17 years. In an era when the elite college football programs have more resources than they have ever had, Saban has kept the Crimson Tide on a level above their competitors. A hot topic in the SEC concerns whether Saban's success is getting his competitors fired.

"Consistency and performance define success," says Nick Saban. His Alabama team is looking to avoid another semifinal loss in the College Football Playoff. Kevin C. Cox/Getty Images

Just the fact that the Alabama dynasty will begin Year 9 is proof of its existence. Not many dynasties survive that long. Oklahoma made it under Bud Wilkinson from 1948 to 1958. Alabama, Oklahoma and Michigan did so in the '70s. Miami stayed atop college football under three head coaches (Howard Schnellenberger, Jimmy Johnson and Dennis Erickson) from 1983 to 1992. And the mother of them all, Florida State, lasted from 1987 to 2000.

The Seminoles began to slide when coach Bobby Bowden's top assistant, offensive coordinator Mark Richt, left after the 2000 season to become head coach at Georgia. That scenario fits Alabama a little too well. Saban's top assistant, defensive coordinator Kirby Smart, is leaving after this season to become head coach at, yes, Georgia.

History rarely repeats itself word for word. But the general point, that losing a top assistant can produce a seismic shift, remains salient. Bowden promoted his son Jeff to replace Richt just as the Seminoles' quarterback pipeline, in which a recruit spent two or three seasons learning on the sideline and then took over the team for two seasons, ran dry. The Florida State offense was never the same.

To replace Smart, Saban has hired Jeremy Pruitt, the former defensive coordinator at Florida State and Georgia and a former secondary coach under Saban. It stands to reason that the transition will be minimal, but Smart, who turns 40 on Wednesday, has worked for Saban for 11 of the past 12 seasons. He didn't have to guess what Saban wanted.

There's also a considerable number of people who expect offensive coordinator Lane Kiffin to be working elsewhere next season, most likely the NFL, but Saban goes through offensive coordinators the way Hogwarts went through professors of defense against the dark arts.

Staff changes are not the only reasons dynasties fall apart. Complacency can infect the meeting room. Here, Saban has proved his ability to adapt. When his campaign to curtail the up-tempo offense failed, Saban not only hired Kiffin to incorporate more of it into the Tide offense, but he also changed how he recruited defensive talent. Out went the run-stopping and pass-rushing specialists up front; in came more versatile players who could do both. Out went the physical safeties better at crowding the box than covering the seams downfield; in came corner-sized defenders who can cover downfield. The results speak loudly for themselves.

Complacency also can affect the locker room, which is one of the things that affected Wilkinson at the end of Oklahoma's 11-season run from 1948 to 1958. The Sooners went 107-8-2 (.923) in that time, including a 47-game unbeaten streak, the FBS record.

"We won so long," Sooners All-American Leon Cross said in a biography that Jay Wilkinson wrote about his father, "and then we got people who really didn't want to pay the price."

Bud Wilkinson's run of dominance at Oklahoma included a 47-game winning streak that remains an FBS record. AP Photo

Complacency would seem to be the last thing that would affect a Saban team. One of the driving tenets of his coaching is that the past should have no effect on what happens today.

"Consistency and performance define success," Saban said before the SEC championship game. "It's not easy to deal with success. It's not easy to deal with failure. So to have the right psychological disposition to be able to sustain all those ups and downs and look at every one of those challenges as a test, not a sign of what's going to happen. ... That's the only way you have a chance."

Wilkinson's run in the '50s also was slowed by a pair of NCAA investigations, which is also what took down Miami in the mid-1990s. While Alabama ran afoul of the NCAA in 2007, Saban's first season, when athletes in football and several other sports used the athletic department's account to get textbooks for their friends. Saban had nothing to do with that. Otherwise, he has made a career of living by the NCAA manual.

Dynasties also end because head coaches falter. They get sick, as Notre Dame coach Frank Leahy did at the end of the Fighting Irish's dominant run from 1946 to 1953, when they went 63-8-2, a .877 winning percentage. Or they get old, as Bowden did, or they get old and sick, as Woody Hayes of Ohio State did in the mid-1970s, as Bear Bryant of Alabama did at the end of the '70s. Bo Jackson's decision to play for Auburn instead of Alabama in 1982, which would be Bryant's final season, is regarded as, if not the beginning of the end, a confirmation that the end was nigh. Bryant would die months later of a massive heart attack at age 69.

Saban turned 64 on Halloween but looks and acts five years younger and has given no indication that he is going to slow down any time soon. He is signed to coach for six more years, which would get him to 70. The larger question with Saban is not when he will lose his edge but when he will lose his desire. He has groused about the unreasonable expectations of the Crimson Tide fans, as if a 9-3 record will compel them to get out their pitchforks and torches. That is the bed he has made.

It is possible Alabama will go 9-3 in our lifetime. If a quarterback doesn't appear who can replace Jake Coker, if the untested Damien Harris can't pick up the mantle left behind by Heisman winner Derrick Henry, and all the ifs that every coach faces every season, it could happen in 2016. Football provides no guarantees, not even for a team coached by Saban. That makes the current dynasty that much more remarkable.