The squad isn't really ageing to be fair. The first team maybe, but the squad has plenty of youth in it. Pickford, Kenny, Holgate, Davies, Baningime, Vlasic, Lookman, DCL, Dowell, Onyekuru could all be first team regulars next season. That's almost an entire team with an average age of about 21.
It's not a novel idea, we've been trying to do it for years - Lukaku, Stones, Barkley, Deulofeu etc were the last lot we had, and we've invested heavily in the current youth set up. The problem is finding players who are both good enough and willing to hang around long enough for us to reap the benefits. DCL is older than Gabriel Jesus for example, but one of them is a regular Brazilian international who is a key player for the Champions, while the other one isn't allowed to be criticised when he misses from 1 yard out because he's only a young lad. Getting the very best young players is not as easy as it sounds, we're taking punts on the likes of Sandro but it's very different to bringing in top class prospects.