Hear me out but I actually think De Bruyne is just as important as Pogba would be, if not more.
I look at Pogba as a luxury, what team on earth could boast two players like Pogba and Yaya alongside eachother? It'd be immense, but Yaya would still be well served with some more defensive solidity by him just as much as he would be with more more mercurial class.
De Bruyne on the other hand, with Sterling and Silva, is an absolute wet dream of service for Kun. Like it or not our team flows through and lives and dies by Kun Aguero. The more options we feed him the better, and those three would give any team in the world fits. Pogba would too, but idk how much exactly it would benefit our most important player. I honestly think Aguero could bag 40+ goals with that service and would be in the short running for Ballon D'or.