Continued success is all about replacing the departing stars. Ferguson, I must say, for all his unlikeability, had no compunction about going out and getting the best replacements (even if he had shipped some players out himself).
Who replaces Dave? Is Foden ready yet? Could Mahrez do a job?
Get the best, or a decline in standards will follow, as happened to us when Allison got rid of a fine late 70s team and replaced them with Bobby Shinton, Stuart Lee, Stepanovic, and the like. United have gone out and got some crap.
The question is - who can possibly replace Dave?