Are all the A380 issues now solved? I wonder what routes have the highest priority... or the lowest. Assuming a breakdown happens in Australia.
A good question, but 'it depends' on where the fault occurred because QFi A388s at present only operate to or from DFW, LAX, LHR, MEL, SYD and SIN.
If a problem develops in London, it's inevitable that QF2 will get the bullet. QF cannot normally rustle up a spare A388 at LHR. The change to QF9/10 to a far smaller B789 limits the number of 'own metal' seats ex and to there to provide rerouting for affected passengers at short notice. Load factors on 9 and 10 are apparently good most days.
Fatigue regulations mandating particular rest periods, and limits on how many hours per month air crew can work, may come into play.
Aircraft have so many cycles (takeoffs and touchdowns) before they need various maintenance. QF spent millions to build new hangar(s) in LAX, and that's some of the reason why the MEL and SYD QF11/12/93/94 flight layovers are so long. Other reasons may include airlines believing evening departures from LAX to Oz sell the best to businessmen and women occupying the costliest seats, and airlines considering the SYD curfew as it is a major constraint.
To hazard a guess, QF35/3, the MEL - SIN and return local flights may be the lowest priority because QF operates other flights ('the 1/the 2', plus QF37/38/51/52/81/82 and JQ7/8 to name some from or to our east coast) and it's fewer air kilometres than DFW, LAX or the through flight to and from LHR. The major competitor (SQ, including LCC TR) has more flights than QF on this popular route and while whenever I travel SQ seems to be close to full, published load factors show that in various months, one or occasionally both directions have at least 15-20 per cent of seats unoccupied. One assumes QF only puts its passengers on a key rival as a last resort.
I don't work for an airline, so there may be other determinants as well such as minimising inefficient aircraft usage or the number of affected passengers and keeping down extraneous costs such as having to provide hotel accommodation, meals and transfers. And there's the welfare of staff, who may have familial or other reasons not to want to be stranded for days a long way from home.