I disagree. While it is unlikely that anyone will play 5 seasons, I think there is a chance that a player could stay at NU for 4 years and still average 17 ppg or more over their career.
As evidence, I looked over the
Big Ten career scoring leaderboard for some comparables, focusing on recent players:
Zach Edey: 17.9 ppg over 4 year career, 2392 points (and counting)
Luka Garza: 18.2 ppg over 4 year career, 2306 points
Trayce Jackson-Davis: 17.9 ppg over 4 year career, 2258 total points.
Lamar Stevens: 16.3 ppg over 4 year career, 2207 total points.
In looking at their year-by-year scoring, one commonality is that their last 2 years were significantly better than their first 2 seasons. I think this allows a player to not quite "draftable" after their 3rd year, but still in a position to set a career mark with a good 4th season.
Now, do I expect Boo's record to be broken in the next 5-10 years? No, probably not. But I don't think it is one of those "unbreakable" records. It just takes a player who decides to comeback for their senior year at NU, foregoing the draft and the portal. Also helpful if NU makes deep runs in the Big Ten and NCAA tournaments during his career.