Not sure of their draft status, but the early 80s Gino teams had many frosh/soph leave early, but those teams also had some very good role playing upper classmen. And, the early departing players all left with an NCAA championship.
The Sioux will have to win with highly skilled underclassman and a few, very few upper classmen. There are other teams in the same boat. Hit a year with frosh forwards equal to last year's along with the experienced D of two years ago and they probably win the NCAAs.
One positive, with so many leaving early, the classes may start to become more balanced, and we won't have those 10+ sized freshmen classes.