The 2 are unrelated... Enzo is exactly what we need in midfield to partner Casemiro, and is a truly future world class midfielder. We already have 3 attackers who offer what Gakpo can, but are each better than Gakpo, and then also have Antony on the right and Garnacho coming through who are different.
Let's talk about the bolded bit. I agree that eventually he'd be a great replacement for Casemiro but I don't see how exactly this is going to work for the next couple of years.
As I see it, the functions in both Arteta and Ten Hag's midfields are quite similar. I think both can adjust depending on the specific players at their disposal but here's the template:
CM1: Deepest of the midfielders in that 3-1 build up structure. CDM type player but must be able to link up effectively. (Casemiro / Partey)
CM2: More attacking / box to box type player. Stays a little bit further up during build up dynamically dropping deep creating the extra man sometimes. Eriksen, Xhaka play this role.
AM: Your standard #10. Bruno is a little more of a goal scorer and Odegaard is more of a playmaker but it doesn't matter enough for the big picture to change.
For Argentina, Enzo played the role Casmeiro / Partey played and he was very effective. He's not really a ball carrier and can't dribble, his skill is in dictating tempo, making himself available for the pass, standard deep lying playmaker stuff.
In this case Casemiro will have to play B2B and he might be okay in that role but I question if that's what we want. Also changing the role of one of the best midfield players in the world to accommodate Enzo is a bit silly in my book.
Ideally, in my book, we want a guy like FdJ or Bellingham to partner Casemiro and not Enzo. In theory even McTominay would be a better player than Eriksen in that role if he can just get his act together.