There’s young players no doubt. Kovacic and Bernardo also as the ones you mentioned who are going to take some serious replacing. Also a lot of players entering 30 some of which are very injury prone. But like I said the man tasked to do it is a man unknown to us.It's not as old as you make out. Kev, Gundogan & Walker and that's about it.
Gvardiol, Foden, Haaland, Bobb, Doku, Savinho, Rico all very young. Loads of promising youth coming through, plenty of cash and we're the best run football club in the world. We're a couple of players away from having a squad for another 5 years plus.