Dutchroll,
The point is Qantas is exposed to all the same factors as the operators involved. Natural disasters, high fuel prices etc... Qantas remain profitable on diversity. The reason the others are not profitable is that their management have made far worse decisions than for not choosing an aircraft that is a fit for only one route in the network. The 330 is a better all-rounder within the Asian region (JB knows this), the 380 maximises capacity and passenger comfort on european routes, as well as being competetive trans pacific.
The 787 promised to do all the 777 does and more to be competetive on shorter routes which would allow it to fill the shoes of the 330 and 777 at a lower operating cost.
Why would they not trust boeing to deliver on the 787, they did with the 777? (and the 747) The fact that its not working out is more boeings problem than Qantas poor management.
The downside at Qantas right now is obvious in the other threads to do with staff issues, which is going to be more of a concern than aircraft types in coming years.