City will potentially lose Sterling and Jesus, leaving Mahrez, Foden and Grealish as their wing options. No doubt they'll buy someone else, but neither of the three they have bring what Sterling brings to the table, in that he has inteligent movement inside the box and is consatntly a threat in behind. You could agrue that Haaland will offer the same thing but you'd imagine he'd be starting through the middle.
From Chelsea's point of view, if they get Sterling, he'd be a fantastic buy and immediately be their best attacking player, in my opinion.