[wolf78]

It is also structurally less efficient than the 747.

While I agree that a KC-380 makes little sense, the claim that the A380 is structurally less efficient than the 747 is not exactly true. Because quite the opposite: it's very efficient as a passenger aircraft and with its ovoid cross section makes optimal use of its interior space - for passenger transport, that is. The pear shaped front end cross section of a 747 is a compromise when it comes to carrying passengers and carries a weight penalty. It's as a freighter that the 747 truly excells, because that was it's primary objective and that's when the design decisions make sense.

In short:
A380 - Efficient passenger hauler - mediocre freighter
B747 - Outstanding cargo aircraft - outdated for air travel.

[Paleo Conservative]

While the 747 ins’t the ideal cross section for a passenger aircraft in its size class, it still has a better CASM than the 777. Also the 747-8 will have considerably better performance than the proposed and abandoned A380-7 shrink of the A380-800. Unless a more optized 400-500 seat passenger plane is developed at a cost of $10-$20 billion, the 747-8 still works pretty well for its niche. With the increase in space allocated to business class seating in recent years decreasing passenger counts plus the increase in the size of the cargo bay, the 747-8i will be able to carry more revenue freight than the A380. In fact Emirates is getting a fleet of 787-8F to handle all the freight that can’t be carried in the belly of their A380 fleet. The main problem with the 747 is the width of the seats in the standard 10 abreast economy configuration.