"I don't think A380 is realistic for NW. When aircrafts are leaving 1/2 full on the current widebodies, filling A380 would be a challenge. Remember guys, there are still some usable 747's. "

Which routes are these? Looking at the load factors for Atlantic and Pacific, seems they've been holding in the 80% - 85% range (except for SARS last spring). Considering normal day-of-the-week fluctuations, in a practical sense you don't see load factors get much higher than that. They have to be sending a lot of full planes out to get those numbers.