Well you put it so nicely! I don't actually smoke....anything, in fact I'm a rabid anti-smoker. But back to the point. There are 1294 B747s, even in competition with trijets, they sold that many. The 747 cannot carry on indefinitely- it is a basic mid-60s design. In 20 years, it will have no sparkle anymore (a 60 year old design). With aviation growing at more than 5% pa every year, even allowing for larger medium aeroplanes (inc.777!) nibbling away at the bottom of the mass mover market, the A380 will have no competition. The 747 will not be able to match seat/mile costs. So it will have the market to itself. I see no reason why, in an expanding world market, the A380 should not top that figure. As a big people mover, it has no competition, and stretched, it will wipe the market clean. It will sell- they're all looking at it, and waiting. There will be a sudden rush of orders. Look at the DC10, fine aeroplane, but it couldn't match seat/mile costs of the 747- so what happened to it? A nice parking spot in the desert.
Where did you get the figure of breakeven of 600? It started at about 240 and went up, but I question 600? Is that your assumption?
I'm off on my hols now, so some of you blinkered people can now convince yourselves it's doomed without argument!