With cable/network revenues, it's almost rendered irrelevant. Even merchandise licensing/revenue is just a drop in the bucket now.
When you can se the up a primo home theater for 2-3 years worth of season tickets and just pick a game or 2 to go to... becomes an easy choice.
Also, geographic populations make a huge difference in attendance. There's about 200,000 people within 2 hours of Iowa City...compare that to about 1 Million within an hour of Lincoln (who still also almost never actually fill the stadium). And they have zero competition from other D-1 programs in state or within 4-5 hours.
You add it all up...you'll see reduction in capacity, bigger seats, prime "box seating", and higher ticket prices.
It's going to become mostly an occasional "event" to go to games, unless you live close, have significant discretionary $, or no longer have work/family responsibilities.