I think most of the teams will be in the same boat, some might be bit younger than others.
On a high level If I divide our squad into few categories, it would be like this
We need a CF as a high priority and probably next season it will be RB.
We have 4 players 30+, 2 of them are not needed and good chance will be gone. If we sign Hojlund and Greenwood comes back then they will be first team players and they are at very good age.
Core player | Age | | First team players | Age | | Squad players | Age | | Might be sold | Age |
Mount | 24 | | Antony | 23 | | Garnacho | 19 | | Maguire | 30 |
Rashford | 25 | | Dalot | 24 | | Pellistri | 21 | | Fred | 30 |
Martinez | 25 | | AWB | 25 | | Sancho | 23 | | McTominay | 26 |
Onana | 27 | | Martial | 27 | | Malacia | 23 | | Van de Beek | 26 |
Bruno | 28 | | Eriksen | 31 | | Lindelof | 28 | | | |
Shaw | 28 | | | | | | | | | |
Varane | 30 | | | | | | | | | |
Casemiro | 31 | | | | | | | | | |
Haven't checked Liverpool squad, would be very surprised if they have lot of old players. Their attackers are at good age except Salah and he is still going strong.
Also one point about "we are set for years" is, things change very quickly in football. For example 2-3 season ago we had Rashford, Martial, Greenwood with 2 of them scoring 20+ and Greenwood scoring 17. Just last year, we had 0 attackers as Martial was crocked, Greenwood was gone and Rashford was at his lowest point in his career.
Saying all that, Arsenal are in very strong position and have done very good job in shaping their squad.