I really liked the look of a McKennie—Adams—Musah midfield. Despite it being the first time any of them played together in midfield (in the previous match McKennie and Adams played in together, Berhalter was still experimenting with Adams as a sort of inverted right back) and no preparation time, they looked cohesive as a unit. If Musah decides to stick with the USA, I can see that trio being the basis for the American midfield for more than a decade to come. If not, I'd expect Brenden Aaronson at RB Strasbourg to grow into the role (and I expect him to be an asset moving forward regardless for his creativity and ability to break lines in the final third).
As for the attack, obviously it was a loss not having Christian Pulisic and Josh Sargent available (although I think it's gotten to the point where any US manager should have a solid contingency plan for when Pulisic isn't available), I'm not sure what Berhalter was playing at with Lletget as a false nine. It all seemed too clever by half, especially considering the fact that, even without Josh Sargent, he had actual center forwards available. Hopefully, that'll be the last time anyone sees that experiment.