Argentina looks ready to win the WC. Italy is in need of a rebuild.
Some of the euro squad needs to be phased out. Emerson, Florenzi, Pessina, Insigne, Belotti, Chiellini, etc.
Tonali, Calabria, Locatelli, Lo. Pellegrini, Zaniolo, Scamacca, Bastoni need to be more and more important.
Pessina is only just starting his career so disagree there, but he shouldn't be starting key games for sure. I think we all know that line up is not the Italy team of the next phase, but tbh Mancini was always going to pick what was in best shape and most "deserving", i.e. the sentimental choice, including Chiellini. Bonucci on the other hand simply has to play as there is no one close for quality and experience. I'm not his biggest fan but he's largely been very good for Italy.
The issues with winning games will remain whilst the attack does not get fixed. Players like Berna and Belotti are not going to be leading the line, they need to be struggling to make a 23 man tournament squad. You see the difference here tonight with with Argentina had up front, but that difference has been around for years, not just recent times. Argentina have arrived as a strong team, their recent results show it. Italy feels like the end of a journey, but it's always better to win something along the way.
It depends if you think Mancini can galvanise largely the same group of players before, plus the ones you mention coming in. The Nations League is obviously going to be a step too soon for this team to compete, he will maybe have to try a few things, but I think the NL is only really important to those who win it anyway, a bit like this glorified friendly. As Italy won't be going to the WC like the other teams competing they have to show a bit of pride and competitiveness, in a very difficult group. This is still Italy and they can't just be making the numbers up.
Without changing coach you aren't going to get a hard reset like there was when Mancini took over. You look at players such as Immobile and Insigne (off to MLS) and think that they'll be occasional squad players at best. There definitely needs to be more faith built around those players you mention. There is no other choice as it's simply the next generation most ready to play.
Injuries are also a factor. We don't know what Chiesa will return to. Spinazzola is not young and will have more issues. Zaniolo is a question mark. And Verratti, you just can't rely on him to be fit. If you draw up an Italy squad on paper it looks good but apart from the Euros it often doesn't seem available. I think we all know that with a couple more key injuries then Italy didnt/don't have the depth to win tournaments, this is an ongoing issue compared to other leading NTs.
They can put a competitive squad together but momentum is a big thing, maybe even bigger for this Italy is availability.
GK) Donnarumma, Meret, Cragno, Carnesecchi
DC) Bonucci, Bastoni, Mancini, Toloi, Luiz Felipe, Gatti
DR) Di Lorenzo, Calabria, Lazzarri
DL) Spinazzola, Dimarco, Emerson, Biraghi
MC) Verratti, Jorginho, Barella, Pellegrini, Tonali, Locatelli, et al
WF) Chiesa, Zaniolo, Berardi, Raspadori, Insigne, Bernardeschi
CF) Immobile, Belotti, Scamacca, Kean
The problems are evident around the strikers, it's harder to win games when you don't have a decisive attacker like a Messi or a Kane to win games, Italy try to do it a different way, and it can be profligate and costly. The team seriously needs either or both of Raspadori or Scamacca to step up, but that seems a lot to ask for their talent. In the right team both could be very useful, however, more than Immobile ever was. The effectiveness of the attack is still going to be determined by those players in the wider and supporting forward positions.
In defence it's obvious that Bonucci is going to get another cycle, surely with Bastoni. Bastoni's mid-term partner will be someone relatively average in comparison to the Bonucci-Chiellini (and Barzagli) partnership Italy have been lucky enough to have for so long. You can't take it for granted that the team can fall back on the defence anymore. Maybe one day the Bastoni-Gatti defence will be a similar partnership but that is 2-3 years away from even becoming an established reality. The fullback areas continue to look problematic with an injury or two.
After that the squad is banking on young players emerging, which does happen and Mancini will give a chance with time and space. We're looking at players like Fagioli, Ricci, Okoli, Rovella, Lucca, Bellanova, Pirola, Udogie, Cambiaso, Seb Esposito, Papetti, Scalvini, Vignato, Cancellieri, Calafiori. Someone will also emerge at 25+. But those players may be needed sooner than expected.