Schmeichel believes the man who replaces Ferguson, 66, must be a former United player who has a strong bond with the club - such as Blackburn boss Hughes or Sunderland manager Keane.
"It would make sense to talk to Sir Alex and say 'we don't want you to retire but let's do a plan here and bring your successor in'.
"The successor could work with him for a year or even five years. That would bring continuity.
"United have reached a point where they are no longer a club but an institution.
"To have someone coming into that institution with totally different ideas will upset what's been going on."