"You're saying to make an older aircraft design more efficient than a newer model that it has to be redesigned from the ground up?"
The A380 is based on nothing that Airbus, or anyone for that matter, has ever built. It is a brand new design that has been built from the ground up. Some may try to argue that Boeing could simply extend the upper deck of the B747 all the way, but the A380 is not based on the B747. A few years Airbus was negotiating with McDonnell Douglas on a cooperative effort for a super-jumbo dubbed the MD
-12, but that fell through, and so Airbus has designed the A380 from scratch, and is now building it. Airbus has not taken an older aircraft design and made it better, rather has built a new plane from nothing.
While the B737NG is not a plane that was built from the "ground up" entirely (it is even stated that "the only thing "old" about the 737NG is the fuselage") it is in fact a "new" aircraft. The B737NG is a new design, having new engines, new wings, new flight decks, ect, ect.
The truth is, to be competitive, new aircraft must be built from nothing. Look at Boeing’s B777 for another example. It was not built from the B767, it was a totally new design, and yet in the beginning, Boeing had thought about marketing it as the B767X, but then went to the B777. If Boeing had used the older aircraft design of the B767, the B777 would never have been as efficient as it is. Look at the B767-400, even since it is a newer model of the B767-basic, it still is not as efficient, and will never be as efficient as the B777, (built from the ground up).
What I am saying about Boeing and their future super-jumbo projects is they will not be able to simply extend the B747 as it is today, to truly be competitive they will have to build a brand new aircraft. You can only extend an aircraft so far. The B747-500/-600 projects show this, in that the minute changes would not bring something anywhere close to a competitor to the A380. I truly believe that Boeing will play it's cards right and see what the A380 offers, and if the market is in fact good enough for many super jumbos, we might see the BWB in the future, or perhaps the re-emergence of the MD
-12 (now that those plans are in the Boeing archives). But the truth is, the B747-line has seen it’s maturity, it is time for a new model, a new jumbo/super jumbo from the Boeing line.