Are they? Qantas flies the A380 to and from a number of congested airports (SYD, LHR, HKG etc) and on routes where its range and payload are important (DFW, potentially SCL and JNB once the 747s go, although I think 787s or 777X/A350 would be better for the last two), and where frequency is less important than arrival and departure timing (anything trans Pacific or to Europe). The markets it operates in are also quite different to the European market, which is highly fragmented given the number of airlines and hubs available to travellers with only a short connection, killing any revenue premium for most airlines - Qantas dominates Transpacific, and is P2P to HKG, and is increasingly locking in premium traffic from Australia which can fill a large number of premium seats that attract a revenue premium.
Yes, QF will need to retire the A380 and replace it with more efficient twin engine planes. I'm not arguing against that. But, I don't think that the argument that the economics of Air France and Qantas are the same, in respect of the A380, is right at all. I'd expect Qantas to be one of the later airlines to retire the A380.