All the MERGERS also meant you were down to three big hub-and-spoke legacies that all figured they were too big to fail and had more "leverage" to demand a bailout than they did in 2001. So they went their merry way in making things worse for passengers in the name of increased profits and then spending most of that on share buybacks.
I've said all along that I think we'll need government-mandated minimums on the seating because airlines won't be reasonable about it on their own. Someone like Spirit will try to push it just a bit more and, if they get away with it, it puts pressure on others to join the race to the bottom.
We also shouldn't let up on all-in pricing. We've had airlines like Spirit just invent airline-imposed fees and make them look like taxes. They'd like nothing better than to advertise $0 fares in large type but have them price to $50, minimum, after taxes and hidden fees and then start the "optional" fees on top of that.