It only took 10 years, but American Eagle parent AMR (NYSE: AMR) finally came to terms yesterday with the reality that its cost structure and debt levels would be uncompetitive next to its peers.

AMR has struggled with a plethora of issues. Its labor costs are arguably the highest in the industry and negotiations with the workers' union has been going nowhere fast. AMR's fleet is relatively old compared to that of other national carriers United Continental Holdings (NYSE: UAL) and Delta Air Lines (NYSE: DAL). An old fleet isn't necessarily a problem, but older planes tend to get considerably worse fuel mileage, which is also hurting AMR in the pocketbook. Finally, the company is sitting on a monstrous pile of debt totaling $11.6 billion that it never would have been able to crawl its way out from underneath. In reality, the AMR bankruptcy seemed like a foregone conclusion to many.

What the AMR bankruptcy does signify, however, is a clear and definitive changing of the guard from a national-carrier-dominated industry to regional carrier supremacy.

Think about it: every major national carrier has declared bankruptcy in the past decade -- some even twice! US Airways (NYSE: LCC) in 2002 and 2004, United Continental in 2002, and Delta Air Lines in 2005. This isn't to say that regional airlines haven't had their own issues (Mesa Airlines, Hawaiian Airlines, Aloha Air), but regionals have been considerably quicker to adapt to changing consumer travel habits and are far less affected by rapid economic shock.

Take Allegiant Travel (Nasdaq: ALGT) as an example of why being small puts you at the top of the mountain these days. Allegiant's fleet is similar to AMR's in that it's older than many of its peers' -- but this actually puts it at an advantage to the national carriers. Allegiant purposely buys used planes in order to keep its cost structure down. That's not an option for Delta, United Continental, US Airways, or even AMR, which recently placed an order for 200 new 737s with Boeing (NYSE: BA), which it says it still plans to go through with.

Another differentiating factor has to do with just how each company operates its routes. Allegiant, because it's so small, has the ability to shut down routes altogether if fuel prices rise too rapidly or passenger load counts dip too low. National carriers simply can't shut down popular routes without the fear of alienating their customer base.

The final reason Allegiant does well is because many airline consumers could give a damn about loyalty. The almighty dollar is what rules their decision-making process a lot of the time, and what most potential passengers are looking for is the lowest-priced flight possible. With alternate fees built in elsewhere (baggage, meals), Allegiant is able to pass along these savings at a markedly lower price than the national carriers can offer.

Another airline capable of undercutting the national carriers yet somehow able to keep customers loyal is Alaska Air (NYSE: ALK). Many airlines offer mileage credit cards, but few have had the success in luring customers and keeping them loyal like the Alaska Air credit cards have.

With AMR's bankruptcy, I can only assume that the talk of airline consolidation is right around the corner. As for me, I think the solution lies in breaking some of these national airlines into smaller components before we wind up in the same situation all over again in another five to 10 years.

What's your take on the airline sector? Are regionals the way to go or will national carriers reassert their dominance? Share your thoughts in the comments section below and consider adding these stocks to your free and personalized watchlist to keep up on the latest news in the airline sector.