I agree that many coaches would love that type of advancement, but name the 'many' current head coaches that have resumes that look like that? Claeys first time being a head coach was at a P5 program at the age of 47. Many coaches are born natural leaders and want to lead at a young age. I don't think Claeys fits that mold. Look at the other head coaches in the B1G. The following is the age of their first head coaching experience:
Illinois - Lovie Smith - NFL - 45
Indiana - Tom Allen - High School - 34
Iowa - Kirk Ferentz - College - 35
Maryland - DJ Durkin - College - 38
Michigan - Jim Harbaugh - College - 40
Minnesota - PJ Fleck - College - 32
Michigan St - Mark Dantonio - College - 47
Nebraska - Scott Frost - College - 41
Northwestern - Pat Fitzgerald - College - 32
Ohio St - Urban Meyer - College - 36
Penn St - James Franklin - College - 38
Purdue - Jeff Brohm - Arena - 30
Rutgers - Chris Ash - College - 42
Wisconsin - Paul Chryst - College - 46
So Chryst and Dantonio are really the only two that are comparable in college to Claeys. Lovie was also similar age but worked his way up in the NFL. The average age of the current B1G head coaches first head coaching job is 38, nearly 10 years younger than Claeys was.
On top of that, if Kill didn't have health issues, I think he'd still be here and Claeys would still be the DC. I don't think Tracy ever really wanted a HC job, but gave it a shot because it was offered, and increased his pay by 2.5 times. Based on everything I've said, plus what happened last year, I think it's an easy prediction to say he'll never be a HC again.