I absolutely agree that WN's new DAL service will change the market in N. Texas and have been saying that for months.
WN will be the price disciplinarian in the market whether Bob Mann sees it or not. Spirit may offer lower fares but it doesn't have the frequency to discipline the market. It siphons off a few passengers which the legacy carriers recognize aren't worth trying to change at fares that low but they create a lot of demand that simply isn't carried on existing flights.
This is nothing new to AA they have had competition before in other markets. Really this is symbolic at best that WN is entering their turf at their home base but they have coexisted with WN for many years in other markets.
what other hubs has AA had WN on a sustained basis? Any other low fare or low cost carriers?
This IS a big deal. It is WN's backyard and the two airports substantially overlap parts of the same metro - more so than any other two major LCC and legacy carrier hubs.
If it wasn't a big deal, AA wouldn't have put up the effort they have for years to force WN into a box which they now are being able to open but with far less gates than they want or DAL had before this all started?
AA has had no other carrier compete in AA's top DFW domestic markets for 10 years and has never had a low fare carrier that has served more than a couple markets with enough frequency to attract high revenue passengers.