donation requirements dropping, I contacted the University ticket office this morning. The article is rather misleading in implying that the entire stadium is somehow "on sale" - it's not. In fact, for the most part... it's sold out.
But note I said "for the most part". There are still seats available in the upper end zones, though they require a $150 per seat donation. Is this down from past years? Yes. That's a function of supply and demand. Nebraska added 6,000 seats this season. Most years, only a few hundred seats become available, mostly because season ticketholders pass away or choose not to renew. I suspect that very few people choose to not renew, but rather sell their tickets on the secondary market. So that cap meant that donation requirements are typically very high.
Thanks to the expansion of the stadium this year, an opening existed earlier this season to get into the stadium for less than in past years. Calling it a "collapse" is misleading, because I suspect this is a one year thing related to the expanded supply. Next season, it'll start moving back up since there won't be any additional capacity.
Is Memorial Stadium at it's ultimate capacity? I suspect it's approaching it, considering the population base in the region. Further expansion would either need an influx of interest (either more people moving into the region or another national championship) or a reduction in price. I don't ever see prices reducing, so I think that expansion is likely complete.
Note I said "earlier this season". If you think you can call up and get seats anywhere in the stadium, you'll be disappointed. Those tickets are now sold out. But a few seats do remain in the upper end zone, if you are still interested.