My mother worked for Delta for 20+ years, I’ve been flying for 30. Let me ask you, has the airline experience gotten better over the last ten years or worse?
Depends what you mean by experience. The worst experiences I've had flying on business (since '87) were right before the internet bubble burst. All the planes were packed, people were stressed, and the planes were old, so you constantly had people reclining into your lap as soon as the plane took off (seats on a lot of the older planes could go back further than they can now). I remember asking a woman to please get her head out of my lap once and she completely blew a gasket. That's all better now, at least in my experience, but as far as amenities go, of course not. The airlines have chipped away as much as possible at those types of things, so it's a much less consumer friendly experience. That, plus the hub system still sucks for getting you somewhere on time (at least on the routes I tend to fly).
I remember watching interviews with the CEO of American (Crandall I think his name was) on business shows back in the day thinking this guy was one of the least likable individuals I'd ever run across, and he was never shy about talking about running the low-cost carriers of the day out of business. (Well, People's Express probably wasn't going to survive charging $29 to get from Pittsburgh to New York, but it was great for us college kids of the day). So perhaps my opinion is jaded by things like that.
Anyway - back to the original point - I don't think the world would miss a beat for very long if an airline or two went BK. Either they'd emerge without their old debts and their secured creditors and shareholders would suffer (and they all took those risks on), or they'd disappear and someone would take their place.