I agree to an extent and certainly in terms of today, but the following line up has plenty of athleticism for example, and I wouldn't be surprised if it's what we see emerge this season, fitness pending.
...................Onana............
...........Yoro....De Ligt...Martinez.....
Mazraoui..Ugarte..Mainoo...Garnacho
..................Bruno...Diallo.......
......................Hojlund........
Compared to today that's taking out Evans, Dalot, Casemiro, Eriksen, and Rashford.
So I don't think overall it's a crisis, but we need more depth for sure, but this feels fairly natural- eriksen and casemiro for example would always have been phased out from next summer.