re: The Airbus is radically different from Concorde
Most of the buyers are not planning to use the A380 for more than 550 passengers. They'll have more room, more comfort than in a B747. Their goal is to make passengers forget they're flying. And there's less fuel spent per passengers.
And I've seen lately how many planes there are at any time in the sky and it's much much more than several years ago. The sky can be loaded with contrails.
If there are fewer planes, and thus bigger ones, that would be better for everybody.
But of course, only a few airports can welcome the plane, so far.