Every cycle, we know, must come to an end.
Even Sir Alex will eventually shuffle off from Old Trafford although you get the feeling he might have to be forcibly removed.
There has been much speculation that Fiorentina's controversial European elimination by Bayern Munich could be the end of an era.
Cesare Prandelli has performed wonders at the club.
In his time at the Viola he has taken them from a team which could barely survive in Serie A to Champions League contenders.
Along the way his side has produced some sparkling football, unearthed new talent, and regenerated key players who seemed to have lost their way.
A pretty impressive result.
It has been the crowning glory of a managerial career which has brought him affection and respect wherever he has been employed.
The question is: has he done all he can at Fiorentina?
Viola fans would argue that there are still a few landmarks to be achieved.
The biggest gap in the Prandelli era is the lack of a trophy to put on display. That is why the Coppa Italia has assumed enormous importance this season.
With the Florentines struggling for league points and now eliminated from Europe, it is the only way to make sense of a crazy campaign.
Some of Fiorentina's best games this year have been in defeat.
In the medium to long-term, owners Andrea and Diego Della Valle would like to see the team compete for a much-coveted third Scudetto.
It would be even sweeter if Cesare was in charge.
However, every manager comes to a point where they feel they can take a team no further.
Only Prandelli will know if that time is now.
Whatever he decides he will always be revered in the Renaissance city for his class, composure, and occasionally dodgy fashion sense.
The Italy job would surely be an appealing prospect for both the coach and the football federation.
Prandelli has done a grand tour on the club circuit and the international game would be a fresh challenge.
He would get to work with many players he knows already and also have the opportunity to put two of his greatest qualities to work—nurturing young talent and revitalising older stars have been the hallmarks of his career.
After the second reign of Marcello Lippi and the forgetful Roberto Donadoni age, his appointment would make perfect sense.
The case for the Juve post is less clear and that is not just the natural anti-Bianconero reaction of a Viola supporter.
Prandelli has worked well at smaller clubs where the expectation level is less and there is time to work your magic.
There is nobody better at sticking to a budget and getting the best out of what is at his disposal.
At Juventus he would face a very different challenge.
Money is less of an issue in Turin than at other Italian clubs but, as Ciro Ferrara can attest, they expect a lot for their investment.
Certainly, Prandelli could rekindle old magic with Felipe Melo and Giorgio Chiellini.
And he would probably try to bring a few old friends with him from Florence.
The likes of Juan Vargas, Stevan Jovetic, and a fully fit Alessandro Gamberini would sit nicely in the Juve squad.
But would he be given time to produce the goods?
Prandelli is a nurturing manager who likes to develop players over time and bring them through gradually. Witness the slow explosion of Vargas or the dosing out of Jovetic's skills.
In Turin they expect their signings to deliver straight away—go ask Diego.
Of course, the boss from Orzinuovi is perfectly capable of being a resounding triumph at Juve.
He is a first-class manager and deserves to take charge of one of our biggest clubs.
In addition, his history in black-and-white as a player gives an emotional attachment to La Vecchia Signora.
These will all be issues flashing through Prandelli's mind.
In homes around the River Arno everybody will be hoping his final decision is to stay at a club which has come to fit him like one of his purple puffer jackets.
The bench will seem empty when he goes.
And with all respect to his rumoured replacements, like Gigi Del Neri and Max Allegri, none of them seem worthy of filling his tight-fitting polo neck.
Life changes, of course, and fans must move on and adapt.
But that doesn't mean you don't try to cherish what you possess and, from time to time, look back at what you have lost with a little regret.