With all of that De Ligt chat, I think our priorities should be:
1. A technical ST that can also play a LW. Rashford/Mbappe/Martial type of player (those are examples, other players are avalible).
2. A backup LB. Either a cheap veteran like Luis or a promising young player that can replace Alba in the long run like Mendy.
3. A plan B striker, who can head the ball. When things go tits up, you bring him on and you can cross, cross, cross (like RM did with Morata in their last Liga win, which they shouldn't have won, but still...)
4. A CB. And this is where De Ligt comes into the play.
5. A box to box midfielder like Ndombele to replace Rakitić and Vidal in the long run.
Those are in order of priority IMO. However, if we do either #1 or #3, the other one moves below De Ligt.