See I still disagree with this. You have to be more specific. It's never been cheaper to fly into cities like NY. Have fares gone up in St. Louis? Maybe. It's hub specific. The issue is not just the oligopoly but at what hubs are airlines competing for seats and where are they not. You cannot say across the board fares are going down or fares are going up. The airline business is a lot like real estate. Real estate on the coasts is at record highs, in the rust belt, scrapping the lows. The "where" in this equation is very important.
On a secondary note, I hope you are not trying to recommend airline stocks because most of them are trading like shit. I still don't understand the main point on this thread. Healthcare, food, and education costs have seen much more inflation then airline fares. And if airlines didn't have corporate expense accounts filling up over priced business class seats, we probably would have nationalized the airline business.
Real estate (as an industry) is different than airline routes because it is intensely and solely local. However, overall real estate prices did go up in 2007 even if some locales didn't. Here PRASM is up uniformly for all airlines at levels never before seen. Unlike real estate, PRASM is an accurate number - like saying the market went up today because the SPX was up. Not all stocks went up today but most did.
My only point is that consolidation has caused increased airfares. I'm disputing your point that it didn't.
I'm not making claims that airline stocks are good investments or that the airline business is a good business to be in.