There is no way at present to predict what the long haul fleet looks like in ten years. QF could really operate twice the number of aircraft on long haul when you consider destinations and frequency. The capex however to buy 26 widebody aircraft is ~13 Billion AUD at list price. That’s just to replace the A330 fleet, no expansion.
Obviously things will change at QF. Post Joyce, the board may decide to actually run an airline and hence commit big to lease a larger fleet. Equally, they may decide to continue to define the airline as a niche premium carrier and have a small fleet with a single daily presence in many markets and leave frequency to the competition on each route.
Right now the math suggests that a new hire in 2023 will have a 30 year wait to command. Assuming 30 shorthaul aircraft and 50 longhaul. Assuming less than a 3% attrition rate per year. (Because you have to consider the average pilot group size over the past 30 years) Assuming 11 captains per plane longhaul/ 8 per pland shorthaul.
QF have alluded to the A220 being the future of domestic travel. That aircraft is not a mainline job. The (so far uncertified) A321XLR is mooted as the replacement aircraft, but they have so far only committed to 20 to replace 74 737 NG aircraft.
If the fleet withers to 50+30 you can see that the total captain pool is 740 + C&T pilots. If QF loses 60 pilots/year (which it doesn’t right now), the time to get from number 2500* to 740 is 29 years. You can play with the numbers to see which fleet size scenario yields a reasonable time to promotion.
Factor in the next generation aircraft will be arriving about then, and there is no certainty that they will be two pilot aircraft, nor that discretionary air travel will be by then considered to be an acceptable carbon footprint.
* I think QF has 2500 pilots on the list, but that is an approximate number