In my opinion, we need at least two top level players. I'm not all that convinced by Bentancur so far, but I'm not opposed to keeping him for another year or two and seeing how he develops. I think Khedira can only go so much further with us and can be replaced. Can performed exceptionally well against Atletico in that specific hybrid role he had, but was very hit or miss otherwise and if we're not going to regularly play that style then he could be upgraded on. Matuidi I like for his workrate, I'd keep him just for that. Pjanic I do not like personally, but when on form he is great. He hasn't been playing well this season in many games, but I'd be willing to keep him and see how he does with more capable players around him, considering what he has shown.
We definitely need a player or two that can bring the ball forward, we very clearly lack that. We'd improve considerably if we had that ability.