MistaT
I said at the start of last season that no team had ever increased its points tally over 5 consecutive seasons in the PL and it turned out that we couldn't either. Similar, a core of players typically go through cycles of 2-4 years where they are able to challenge/win before falling off and then require a fresh new dimension to uplift the team.
It's less about the respective ages of the players and more about the difficulty in sustaining the effort required to win trophies over such a long period of time, notwithstanding the other changes like competitors catching up and methods becoming less effective. Saka, Saliba, Gabriel and Odegaard will be entering the 4th year of their cycle, and Rice his third. I don't think they have it in them to win without a significant uplift in midfield/attack.
If they were able to win without the major signings we require now, they would have won already over the past few years, and even if they had won, we'd still need to make the signings to keep the momentum going and keep the team afresh.