In the present now, many clubs are beginning to look into prioritizing young players over older players who would make up their team squad for long term purposes. Manchester United choosing to go in that area(more young players) is not a bad idea because it is much better to have a coach who will use his hands to groom the players to the formation he wants, over time they will fit into the position he wants them to be, instead of having older players who would keep messing up without showing good results in the pitch. However, all these would take time before the results would manifest, I believe Manchester United management and fans would trust the process rather than being in a hurry to call for the sack of Amorim when the young players haven't mastered each other playing patterns
Having just young players never ended in good for any club because we also needed few well experienced players those can do better and solid things while clubs facing challenges, no doubt many clubs relaying on youngsters but still they also usually keep few players those give them long time and better results like Luka Modrić in Real Madrid and many other players like him into many other clubs situations are changing drastically because many youngsters in pipeline those are ready to replace.
Now as we see few good changes of coaches in few clubs we will surely have many changes into clubs while we will be having end of this season with this many old players will be replaced and things could be on good level for having good changes.