If Southwest wants to fly long haul, they should just move those flights to the available empty gates at DFW and play with the big guys.
I agree with you, but unfortunately the 5th Circuit Court of Appeals doesn't, and the US Supreme Court refused to hear a case on this issue. Southwest was not flying in 1967 when the airlines at Love Field signed the promise to move to DFW when it was opened. The 5th Circuit ruled that as long as DAL stays open as an airport, Southwest must be allowed to operate there. The city of Dallas has two choices. They can completely close Love Field and tear it down, or they can let it remain open so that general aviation can use it and various businesses at the airport can remain in operation there. There's no way that Dallas will make companies that customize and service private planes move elsewhere.
The 5th Circuit's ruling is a danger to any city in the US that wants to build a new airport for passenger service but keep the existing airport for general aviation and aviation businesses. Currently San Diego, California has the busiest airport in the US that only has one runway. Unfortunately there is no room to build another runway without condemning developed private property adjacent to the current airport. Possibly they could build a new airport further from downtown or convert an existing former naval air station to a commercial airport, but Southwest has already said they won't move. Of course without the authority to force them to move to a new airport, they can't sell bonds.
SAN has tons of abandoned buildings that could be cleared for a runway, but I think they have some environmental issues. As far as the airport goes, its biggest problem is the damned parking garage that the Dollar car rental is just beneath. Its too high, I've rented twice from there this month, and its damned scary seeing planes 45 feet above that garage.
It would be cheaper for SAN to condemn some land and fill some land in and build another runway than to build a very annoying and out of the way airport like they are talking about. DEN thankfully quashed lots of talk about new mega airports in the boonies. McCain wanted (his contractor buddies) to build a mega airport 40 miles south of Phoenix and about 50 north of Tuscon, one that everyone in AZ could hate. The DEN disaster prevented that.