I kind of disagree with that part because at the end of the day the manager doesn't play, the players do. You can be the best manager in the world but if the players are mediocre probably you're going to fail. Italy could even hire Guardiola (hypothetically of course) but that wouldn't mean that we're going to the world cup. Do you remember Ancelotti with Napoli and Everton? Great coach, mediocre players, mediocre results.
Currently the Italian national team is filled with mediocre players, there are no outstanding players, unlike their era in the 2000s. So it is very difficult to be able to revive the Italian national team now, even when it is the most experienced coach, because as you said the role of quality players is very important, and then we discuss the manager. Because now the problem of the Italian national team is very complex, so changing the coach alone will not be able to solve the problem, there needs to be a total overhaul from the roots of the Italian football system, and the process can take years.
Italy has won the World Cup four times but if we look at the current Italian team, it doesn't look like they have won four World Cups. Italy's golden age can be said to have been until 2000 because Italy played excellent football until 2000 but Italy could not achieve anything significant after 2000. In one World Cup season, Italy did not qualify for the main round of the World Cup. Think about it, a former four-time World Cup winner performed so badly in one World Cup season that they did not qualify for the main round. Anyway, Italy has recovered from their bad situation and now at least they are playing decent football but they are not yet able to play the kind of good football that we can see them playing in the semi-finals or finals of big tournaments like the World Cup. Italy should work on these issues and bring about a change in the team's situation again.