Tom Izzo replaced Jud Heathcote at Michigan State.
Greg Gard replaced Bo Ryan at Wisconsin.
Matt Painter was hired on as an assistant to Gene Keady for one year where was planned to take the head coaching job the next year, which still fits the description I suppose.
Keno Davis replaced Tom Davis at Drake after he retired.
Those are the examples I’ve found so far, but it seems quite possible for Duke to promote from within, or at the very least hire a guy who has been a Duke assistant in his career at some point. I know Washington’s current head coach was considered Boeheim’s successor at Syracuse. Will Tubby hand off the High Point job to an assistant when he decides to hang it up? I’d guess there aren’t a ton of coaches who are successful enough to retire out of old age as opposed to losing their edge and getting fired, limiting the amount of scenarios where an assistant is promoted to the head job after the previous head coach’s retirement, but I could be wrong.
But yeah i can’t imagine Ben Johnson took the assistant job here with any intention of staying here so long that he would take the head coaching job after the then 31 year old coach decided to retire after ~3 decades of coaching at Minnesota, especially considering Ben Johnson is likely a year or two older than Pitino.