When you look at what's left, it becomes clear how much investment is needed. But not just big-name players to sell some shirts, but players that actually add value in terms of what they can give to the team.
One thing that is noticeable of what's left is the lack of leaders - Ronaldo & De Gea are pretty much the only two. Arguably Fernandes but not for me.
Most successful teams of late have the spine of the team as integral figures of the side - Man City have Ederson, Dias, De Bruyne, Gundogan, etc.
Liverpool have Alisson, Van Dijk, Henderson, Salah/Mane.
Real a few years ago had Ramos, Casemiro, Modric, Benzema.
I'd say that you probably need more of those leaders to get you where you want to be. The talent can be built around that and what is already there.