Omark
I belive it is debateable whether Boeing cancelled their 747-400QXLR (or some such alphabet soup) because they found the airlines would rather buy 777s, or if the airlines would rather buy A380s and Boeing was therefore forced to retreat.
However, the fact that no US carrier have ordered the A380 can hardly be view as a failure of the aircraft. Besides which, its plain wrong as FedEx have ordered a handful. Since only United and Northwest operate passenger 747s, the US market is not the place where the A380 have to prove it's worth.
The real battleground will be the Far East, where Singapore and Qantas have already ordered the type. It will be far more important for the A380 to penetrate the Japanse and Chinese markets than the US. Now there is a worry ....
A fraction of 747 orders? The order book for the A380 is around the 130 mark, or roughly 10% of total 747 output. Not bad for an airliner that will not enter service for another 2 years....
As for wheter US airports will make the necessary adjustments. Well, if I was the owner of an airline due to operate A380s, I'd give LAX a call telling them of my plans to flog an A380 in their direction. I would also give, say, SFO a call. Between them, I'm sure they'd fight for getting my business and thus opgrade their airports. I wouldn't loose any sleep over that issue.