The A-380's meant for slot restricted airports like Tokyo Narita and London Heathrow, not necessarily the New York to Dallas market. It makes sense on some routes (like Tokyo to London) but not on most. I wouldn't expect Dallas or Houston to rebuild for the A-380 unless American or Continental buy it. And I doubt they will. Memphis might, if FedEx actually takes delivery of them.
As you said, the recent U.S. trend has been for increased frequency with smaller planes and increased flights to European non-hub airports. Most American carriers don't even fly the 747 any more, opting to fly 767, 777s and A-330s overseas. Continental has even begun flying 757s to some secondary European airports from Newark.
A-380 is the last nail in Airbus's coffin, the damn EU Socialist deserve it too, IMO of course! Think I will check the Boeing stock prices today.
Which makes me think Boeing will make sure the 737/757 replacement narrow bodied aircraft will have wing and gross weight options early on in the design and manufacturing process to allow range for trans Atlantic operations. Don't be surprised if the next narrow bodied aircraft has a twin aisle design.
Remember the 757/767 were never designed or intended for transoceanic operations. Back in 1978 when the design process started, they were intended for domestic and other routes with diversion times less than 60 minutes. If Boeing had known back then that the 767 would replace the 747 as the most common trans Atlantic aircraft they probably would have made the cross-section wider to accommodate standard freight containers in its belly. It is the lack of freight capacity that has killed demand even for newer models of the 767 compared to the A330.
But which begs the question. Why are those airports slot limited? Prior to the introduction of the 747 there weren't any aircraft with the range for Dallas to Tokyo or Dallas to London flights. People from the middle of the country wanting to travel to Europe tended to fly first to JFK to catch another plane to a major hub on the other side of the Altantic or to LAX or Seattle to go to destinations in the Pacific. Many of the people flying to Tokyo were actually continuing on to other destinations.
With 180 minute and longer ETOPS, and longer ranged smaller planes, someone flying from Dallas or Houston can fly directly to Seoul, Honk Kong, Bejing or other Asian destinations without first flying through two hub airports first. This decreases demand for 747 or A380s flying from LAX or SEA to NRT.
This process is also happening in the UK with charter operators moving operations out of London airports like Heathrow and Gatwick. They are flying directly to tourist destinations like Cancun and Orlando and various cities in Europe. This eliminates traffic on London to Mexico City and London to Miami routes.
380 will be very popular in the inter-Asian market as well.