I don't see it happening, ever.
There's a big difference between the way a professional program is run and the way a college program is run. Academics, recruiting, evaluation, AAU coaches, scholarship planning, unruly parents, etc. If you want to eventually be a college coach, you need to grow up, from a coaching standpoint, in the college coaching business, so you have both a grasp of the tasks BESIDES coaching, as well as the connections to the prep-school power brokers.
Outside of Larry Brown, i don't know who has moved from the pro ranks to college, and been successful. And Larry Brown was pretty well-connected to the college scene, thanks to his UNC background, prior to going to KU.
Bottom line...i can't imagine Fred (or Hornacek) wants to commit to the grinding lifestyle of college coaching after being where they've been. They've got families and good jobs, and more than likely not much tolerance for sleazy AAU coaches and shoe reps. And i really don't want either of them coaching ISU without putting in the work it takes to recruit at the high D1 level.