American and Crandall hurt Peoples Express with a BETTER PRODUCT--nicer jets, better food, better service at a GOOD price.
I dare say AA, DAL, and United do NOT offer a better product than do Air Tran or JetBlue. TVs in every seat at JB...NICE seats in business class for 25 bucks more at AT...these companies ARE NOT bargain basement carriers with 20 year old 727s. In fact, the 717 is about the nicest ride for a 1-2 hour jaunt I've seen, and the JB TV makes the time pass by pretty fast.
Customer service? YGTBSM! The majors may be getting "religion" now, but in the gridlock days of 2000 they were all notoriously horrible. The good service by the upstarts in the 2001-2003 period has generated a product loyalty that the majors gave up when they started maginalizing service.
Also...you want to do "predatory pricing" while asking Uncle Sam for handouts/loans/guarantees, etc? You can bet your local politicians will get an earful from the LCC leadership on that issue--doesn't seem fair to ask for tax dollars on one hand and then drive another company to its knees (and create lost jobs) while the taxpayers subsidize your endevour.
Will the majors rebound some and compete for markets? I say absolutely. However--look at the SWA and JetBlue market cap. Getting in a race to lose money to make the other guy blink will be the death of the major that tries--the LCCs can outlast you and raise capital, increase market share, and keep their customers in such an environment. United and AA largely drove away the walk up business customer after the 2000 stock bubble burst, and winning them back is going to take a lot more than just a lower fare.
Of course...I may be wrong. I fly AF jets and cargo for FDX...so what the heck do I know.