Rangnick should be interim manager to start the foundation of implementing modern progressive football. Then have a say to appoint a permanent manager (younger) to continue the style of play.
After that, we need him more for the consultant roles to modernize the club football structure. This is to ensure our football side have vision and planning for continuity at the club to identify world class manager, players, youth, medical, science and whatnot.
Let's leave the manager roles to someone younger and let Rangnick to focus on modernize the football structure which is already 8 years too late after SAF retired.