What is the ceiling of any of the new head coaches, if Mickey Loomis is retained as GM

I am aware of that, but his record and performance are exceptional. The clip discusses how he sought to talk to other front office people to get better. A ring and two Super Bowl appearances are pretty impressive. Mick is co-dependent on others because he does not come from the player side.
Neither did Roseman, he started in admin just like ML. Then he was vice pres of player personnel for 2 yrs. Not that could be a name only position because it was a VP . We don't know how much he was in charge of. I think the only one ML is dependent on is the HC and maybe the scouting dept very much like any GM. Very few successful GMs come from a player or personnel side of the game