A Cavs jersey will run $120 for adult sizing, but only $90 for youth. Basketball jerseys are typically worn by middle school through college-age kids. Maybe things have changed, but I certainly couldn't afford $159 jerseys as a poor college kid and I don't see many parents shelling out $159 for a jersey their kid will grow out of in a year.
Again, I'm thrilled they're doing more things like this, because it's sorely needed - I just don't think they'll sell more than a handful at that price point. We can certainly agree to disagree on that.