Talismanic captain Vincent Kompany has already left the Etihad, midfield maestro David Silva is going at the end of this season and all-time leading goalscorer Sergio Aguero is expected to depart when his contract runs out in 2021.
The three players were pivotal to City’s rise and have been part of all four of the club’s Premier League triumphs between 2012 and last season.
The task for Guardiola, whose side look unlikely to defend their Premier League title, is to find players who are good enough to repeat those achievements.
“We cannot deny how important these names have been for the club,” said the Catalan ahead of Sunday’s Premier League match at Aston Villa.
“Vinny is unique, Sergio is unique, David too. These kinds of players are incredible.
“But this club has the duty and obligation to find the best replacements for all of them and as quickly as possible and to anticipate it.
“You have to move on and it has to happen. But knowing how important they were, they helped us to be the club we are now.”
– New City stars –
Kevin De Bruyne and Raheem Sterling have emerged as Premier League stars since Guardiola’s arrival but the presence of the old guard, who have been successful under three managers at City, provided a solid foundation.
“I live nearly the last four years with these guys and I will always be grateful for what they have done for me and the club, in our period and in the past,” said the City boss.
“They were with Roberto (Mancini) and Manuel (Pellegrini) and they were incredibly consistent for many, many years.”
There is great hope at City that their academy will start to provide a regular supply of first-team players and Phil Foden leads the way.
The 19-year-old has been earmarked by Guardiola to step up when Silva walks away this summer.
Some observers believe Foden has not had enough football, given his ability, but the young English midfielder has still made 21 appearances in all competitions this season.
“Phil is an incredible player but he still has things to improve,” said Guardiola.
“Sometimes you have to be patient. But I say many times that when David is going to leave this season we are not going to buy any player in his position because we have Phil.
“We trust Phil. If we didn’t believe in him we might go to the market to replace David, but we have Phil.
“He is the guy who is going to take his minutes or maybe he has to fight with Kevin, Gundo (Ilkay Gundogan) and Bernardo (Silva) who can play in that position.
“It’s the only way to maintain the level as high as possible.”