On the other hand, the current 777 and future 787 planes are easily compatible with current international airport infrastructure, so there's no need for expensive reconstruction just to accommodate the Boeing planes (most airports did the upgrades back in the 1970's to accommodate the 747).
I can't see airports in the middle of the US making the modifications. DFW doesn't currently have any 747 passenger service. I don't think IAH will make any modifications for the A380 either, and both airports were built to accomodate the 747. IAH opened about a year before the first 747 entered revenue service, and DFW opened about three and a half years after the 747 came into service with the airlines. Both airports were built with much room for expansion unlike most other airports in the US. Airlines at IAH are more interested in having multiple departure times to allow more flexibility for their business customers than having one big plane that arrives and departs once every day. I'm sure DFW would just be happy to get one 767 or 777 flight a day for the same international destinations available from IAH.