Has there been a change in the Wright Admendment that allows these airlines (Legend, AA, and others) to fly from Dallas Love Field?
According the SWA:
Travel into and out of Dallas Love Field is subject to the limitations of the Wright Amendment. Federal law prohibits Southwest from offering for sale, or providing transportation between, Dallas Love Field and any point beyond Texas, Louisiana, Arkansas, Oklahoma, New Mexico, Mississippi, and Alabama. see:
http://www.iflyswa.com/traveler_info/wright.html
So, what has changed which allows these airlines to fly beyond the Federally Mandated area of service?