I thought I might just point out a few things...

1. The A380 is not something so much bigger than the 747-400 that it has to be considered a whole new league. Sure, the plane has an upper deck that extends right to the tail, but it's still 10 abreast (same as 747). For example, it's only 2.4m longer than a 747-400. My point: It's not exactly a cruise ship... just yet.

2. Although it's true that some new facilities are required, it will only service the world's busiest gateways so maybe it's about 20 airports which has to go under modification.

3. It has a larger seating capacity. And what's so bad about that? Some routes which are experiencing extraordinary demand throughout the year will welcome the A380. Just ask someone who couldn't get from (say) Tokyo to LA because all the planes were full. Will he mind sitting with 500 other people if it's still going to get him there? I'm sure he won't. Even if he has to wait for an hour for his checked bags in LAX

4. As someone has already pointed out, a larger capacity on each aircraft will free up what little precious landing slots each airline gets from the airport. This reduces the frequency to the major hubs, but also means more landing slots freed up for the airlines which can actually enable them to serve destinations which they would otherwise have been unable to due to slots restrictions.

IMO all this is exactly what people would have said about the 747 (sorry, I wasn't even born when the project was conceived ) and look at what success it has been. Demand for travel will no doubt rise, not fall. Whether this turns out to be a success remains to be seen over time, but count me as one of the optimists...