That Sport midfield of the future, I doubt that it is as good as the current midfield. I have not seen enough of De Jong to have an opinion about him. For the others except S. Busquets, I would feel good about Arthur and Alena being part of the rotation for many years, but I am not yet convinced either is Barca first 11 quality. For Rabiot, I also think he is a good bet to be a positive contributor to the team, but I'd be surprised if he is someone who we would like to start in CL knockout games. O. Busquets and Puig, possibly future 1st team members, but lots of these have not panned out in recent years.
If all those midfielders were on the team now, the best starters would still be Rak, Busquets and Vidal. But the current starting midfielders will all likely be aging out soon.