As a long time business traveller I think there is a major piece of the puzzle that many people overlook in bemoaning the state of the airline biz. Namely, how the US majors and others shot themselves in the foot by eliminating travel agency percentage commissions.
Travel agencies used to dominate business travel ticket sales, and by virtue of their 10% off the top commission had ample incentive to encourage their customers to buy more expensive (e.g., fully flexible) tickets and I can assure you they routinely did so. Enjoying this naive customer behavior, airlines ratcheted up flexible ticket prices to ludicrous levels, e.g., 10X the lowest economy fare. This not only provided an inviting price umbrella for LCCs to come in under, far worse it set up a house of cards in terms of business purchaser behavior.
I think airline managements BADLY misjudged the twin wallops of the internet (eliminated all ability to conceal information about fares, availability and competitors' pricing/inventory) and the unintended consequences of cutting out travel agents from the picture (capping comm's at $25 or whatever it is). Business travellers woke up and realized there was no purpose or benefit to paying $2,500+ return for a flexible Y ticket, say, JFK-LAX, when a $300 one would accomplish the same purpose. With no travel agent to promote high fare tickets and/or conceal the availability of cheap fares (or to poo-poo them as if no self-respecting business traveller would buy one), businesses have en masse moved away from so-called "extortion" fares.
The entire economic structure that was being supported by extortion fares is gone. Airplane leases, industry wages and all other economic rents to the factors of producing air travel simply cannot be sustained at former levels. Sad but true.