Yes, an odd route indeed. There seems to be no limit into what NW will do to protect a market.
I had been told once by one of the yield-management types that it only takes about 10-12 passengers per flight (I suppose this would vary somewhat depending on the aircraft) to make or break a flight...in other words, should NW be able to coax some of AA's customers on the DFW-MSP route, or AA do the same on the MSP-LGA route, it could make the route unprofitable for the other carrier. That being said, I think there are times when you just have to let the competition do there thing and not cut your own wrist trying to scare them away...the A319s could be easily utilized out of LAS to alot of places...and they would be almost guaranteed full...yes, at low fares, but I'm guessing the DFW-LGA flights are going to run at less than 50% load-factor and will rarely catch a business traveler that AA has locked up in both cities. I suppose the next question would be, what markets were sacraficed to get the 319s to fly this route?