You all seem to be forgetting the underlying issue with operating via the Middle East; it would only be viable if Qantas secured rights to fly onwards to Europe. Qantas needs daily services from the Middle East and beyond for the market to work. Flying only to the Middle East does not offer value for Qantas. The traffic would primarily be VFR.
The majority of traffic that actually goes to the Middle East is European traffic. It's not a destination, but simply a transit. People are not specifically going to the Middle East for holidays, they're simply transiting onwards to Europe.
Qantas cannot get traffic rights onwards to London on other preferred European cities.
That is the bottom line. The same applies to China. Qantas has been lobbying to allow travel to China and on to Europe, however has been denied access onwards.
Qantas needs access (and frequent) to London to enable onward European travel for customers, otherwise why would a customer fly Qantas via the Middle East to Europe when they can fly a Middle Eastern airline with a minimum potential two stops to get to a European city?
On Qantas you'd have to fly i.e. MEL/DXB (if an aircraft can make it)LHR/ATH for example or potential MEL/SIN/DXB/LHR/ATH to keep it all QF metal.
That is why Qantas code-shares with Etihad. But for Qantas to operate just to the Middle East - not viable. Also consider that the Middle East market is heavily saturated with capacity. The yields would be relatively poor.