Can't really understand why "the other airlines" besides AA and WN would care either way, except maybe AirTran (who've built up a little presence at DFW ) and possibly CO, who do run Express flights DAL-IAH.
Just like AA stayed out of the fight to keep WN from being born in the late '60s/early '70s: They didn't have a dog in the fight back then as they did not have DAL-HOU/IAH route authority at all and only ran one DAL-SAT rt.
Braniff and Trans-Texas/Texas Int'l had much more to lose back then, as both ran at least a dozen Dallas-Houston flights and BN was heavy in the DAL-SAT market as well (TX/TI did not have NONSTOP authority in that market--they had to stop in Waco, Temple, and/or Austin, as amazing as that sounds in these post-CAB days!)
