Odd as this may sound, Jacque Vaughn is probably too old to really consider him for the KU job after Self. He's already 45, which isn't old, but Self is probably going to coach 8-10 more years, which puts Vaughn in his early to mid 50s when KU starts looking for a replacement (assuming Self retires in his mid 60s as he has suggested in interviews).
If KU wants someone that will stay for 15-20 years, they need to look for someone that will be no older than 47 or 48 in 2028, which means that person is, at most, 40 right now.
Everyone, say hello to Jeremy Case, currently the video coordinator at KU, former player and national champion at KU, son of a coach (father is an assistant at Middle Tennessee State). Case just turned 36, which puts him in the perfect age bracket for this job. He was an assistant at both SE Missouri and Houston Baptist, so he has some D1 sideline experience. I would not be surprised if Case eventually leaves KU again to go and be an assistant (or maybe even the head man) at a smaller D1 school so he can get his feet wet running his own show before returning when Self decides to hang it up.
That's just my guess.