Retrenched Pilots from virtually all the operators will be entitled to retain their relative seniority for 5 years (nominal). Even allowing for retirements, hundreds if not close to a thousand will begin to resign from what they have been doing to survive, and head back to the cockpit. I know I would. Every newly minted CPL and graduated Cadet that have not been inducted prior will have to wait until the last of these pilots have been offered re employment, just to be considered!
IMHO, 5-10 years?
The other real consideration in all this is the way the Labor Governed States are behaving. There is no real appetite to actually enable freedom of movement within Australia from the Labor Premiers. What was once a speculative question could become very real and that is how long QF and VA could actually hang on for if the borders remain closed well through 2021. It could be game over for both of them and the entire travel industry.
Originally I would have expected to be back to normal domestically by Christmas but it is looking pretty unlikely unless the Federal Government steps in.