How do we know it's not already done? Maybe medical was done in Dubai or maybe he flew in & straight back out? How do we know City are not just waiting to finalise a few other deals so all the players can fly to the US together rather than in dribs n drabs? Maybe Monaco want a player in exchange or we're buying more than one from them?
In short we don't, but they're all as likely than it's fallen through. I'm confident it's sorted already & he'll fly out to the US at some point. City have no need to please the flappers, they'll announce it when the feel it's right to do so.