Generally, the first step is to offer ER and VR. After that, if they still still haven't got the required numbers, then it's CR. LIFO is often used but in this case the agreement needs to be looked at carefully. The current situation is unprecedented and I doubt the union was seriously considering the possibility of mass layoffs occurring when it was drawn up.
Expensive retraining would be required to move A380 and B744 crews onto other fleets, and the next type down may be over crewed already. Do you then displace more pilots downwards or put the senior pilots onto the junior fleet ?
A few months ago I posted that QF was in a strong enough position to avoid redundancies, and unlike Virgin, would be able to survive this crisis relatively unscathed due to its solid financial state. Back in May, I doubt anyone expected this crisis to still be going on as the end of the year approaches.