Perhaps.
Part of this issue is resolved because Pep rotates attacking players anyway. I suspect Pep would prefer that Phil had been given more time to rest this season than he has so far.
But also, Kev is 32, plays a dynamic game, and hasn't got a great injury record. Foden will be playing regularly in the best team in the World. He'll likely get more time in the centre, and over the next 18 months, could gradually take over from de Bruyne.
De Bruyne was already 24 when he joined City. If Foden is the key player, in the best team in World football, by the time he turns 25, that's some achievement.