The Azzurri lifted Euro 2020 after a penalty shoot-out victory over England last July but failed to qualify for a second straight World Cup following play-off disappointment against North Macedonia in March.
That led to questions towards Mancini and Italian football over the lack of trust placed in younger players, with the more experienced campaigners such as Ciro Immobile and Giorgio Chiellini preferred.
Mancini subsequently suggested that Italy are suffering as Serie A coaches refuse to provide youthful members of their clubs the opportunities to develop.
Italy faces Argentina at Wembley Stadium on Thursday (AEST) in a meeting between the European Championship winner and Copa America champion, though Mancini appears reluctant to trust his younger players yet.
"Tomorrow will be the match that will end a cycle," the Azzurri boss said.
"It does not mean that 15-20 players will leave, but from Wednesday we will include young players to understand how much they are worth and if we can count on them for the future.
"In the meantime, I must continue to choose the players always with a logical criterion, then courage will be needed because it will be a younger group that will need to be supported in a different way.
"We will not change the whole team, but in the four games one, two, three or four young people will play.
"This will also be a great thing to do. We are trying to work for the future, to improve. If the clubs do or do not let the young players play, I cannot decide.
"We will try to have more knowledge of the young people and we want to do things well, but we certainly cannot pray to anyone if they don't want to do it.
"We managed to win a European championship anyway, despite many difficulties."
Despite not having the likes of Immobile, Federico Chiesa, Domenico Berardi and Marco Verratti to call upon, Mancini expects his side to compete well against Argentina.
Asked if his side will still be able to put on a show, Mancini responded: "I think so, even if we are missing several players. I would have liked to have all the boys here, they deserved it.
"We have a good match ahead of us. It is nice to play this match, Italy-Argentina is a classic of world football and it will also be a tribute to many players.
"It is a great pleasure to be here, not even 12 months ago we were here to celebrate [winning Euro 2020 at Wembley] and for this reason, there is also a bit of emotion."