Lowcur, you got me on that one, but that is the ONLY place I've ever seen that mentioned, and I think Cox was talking out of turn.
DFW Airport has no money! I commute out of there, and fly into there with ATA. It's turning into an expensive ghost town. Terminal D, the new int'l terminal is huge and expensive. I don't think DFW could find the money to cheaply build anything that would fit SWA's needs.
Read the rest of the article. It's plain to see how DFW won't work. Throw in an additional 200+ flights per day and you got gridlock. There's not enough incentive for SWA to split or move operations to DFW.
The Dallas/Ft. Worth area can handle two airports, it can't handle less or more expensive service, including further contruction at DFW.