You might know this, but Boeing has something up their sleeves. They have had a dual decker 747 on the drawing board for some time.I think they have it ready for production. First, testing though If the A380 is a success, then Boeing will have their own double decker. Although it will be a double decker it will not be fully two levels. They can have a new plane ready in about 3 years that is based on the double decker 747.