A solid starting XI doesn't win a league, a solid squad does, so we probably need closer to like 8 players in for 8 players out. If we're being brutally honest then Young, Fellaini, Carrick (obviously since he's retiring), Jones, Smalling, Valencia (because of his age), Lingard, and Mata have to be replaced, and they have to be replaced with players that are likely going to cost on average £35m, probably even higher for some crown jewels Mourinho will want to get. Not to mention players like Herrera, Blind, Darmian and Shaw will probably also want to leave so they'll need to be replaced, too.
Are we going to spend £300m+ in a single window and integrate them all within a single season, and also see a reversal in the deterioration of Pogba, Martial, and Sanchez
? Probably not. Even if we get this 'ideal' of Dybala, Kroos, Sandro, and Varane like the papers want uninformed readers to believe we still wouldn't win the league.