Would he and Lindelof work as a pairing right now? Would be awful inexperienced especially if Dalot is going to feature more as a full back or we buy Wan Bisakka.
In my opinion Lindelöf & De ligt have the same need as martial & Rashford would do upfront.
Martial & Rashford need someone in the middle to help them interlink & allow them to start centrally but drift wide on the attacks. To do this they need a player that can take positions & make runs like Lingard does for us - needing an upgrade as much as I do like him.
The same thing for De ligt & Lindelöf - to unlock their full ability they need to defend wide as possible away from each other whilst having a CB/ CDM that drops in & takes that central role that pushes the attacker to the wider channels & then Lindelof & De ligt can break tackles & play counter attacking balls.
Whilst it's heavily inexperienced - someone like declan rice or a more experienced option who can possibly shield the back 2 whilst dropping in to create a back 3 on the defense is what is needed if we are going for those 2.
On the opposite side - we need a false nine/ aka an AMCF that interlinks our midfield in to front 2; allowing us to attack with a front 3 when we have the ball & only having 2 upfront when we do not - but wider on the channels to receive the counterattack ING balls from two wider placed CB's.
I am okay with Koulibaliy - but these are the type of players I want to see when the squad is built & we need some final pre made players to do the work for us a younger wouldn't. I'm not of the opinion that we have enough quality players around the pitch to suddenly turn ourselves only to players in their prime. Players like Smalling, Herrera, Matic, young for another year, Jones provide what we need from such players.
We still need some more young players that help us move towards the next generation of United - the players I want to see atleast be targeted are neves, rice, de ligt, wan bissaka, Tierney & the inclusion of Gomes & Greenwood.
Whilst not all these players can come within a season & not all will be targeted, I have had some people say this is like Football manager for expecting young players; I don't think so - is ole going to build united or go for a short term options that can guarantee more instant successes? I think it's the first option I see in him & for that reason players like de ligt, wan bissaka & neves are the players I see him targeting in the transfer window much more than a Koulibaliy per se.