Well, probably why not that many people are buying A-380's is because airports are now required to extend the runways if they are allowing A-380's to land / takeoff there. Kennedy International itself had to extend its runways by (I think) 4,500 feet to accommodate the A-380.
Also, I see this plane almost the same as the Concorde. A few nations will buy it, yet in the end it will be so hazardous they have to ditch the fleet.