I don't think you get the point that in the airline business fleet renewal is ongoing, not lump sums and done. Jets are not made to last economically more than 15-20 years, 737s are trashed by 10 years in service, so by the time you are getting deliveries of one fleet you need to be actively purchasing the next otherwise you fall behind the 8 ball. If its going to be $10 bill now, it will be another $10 bill to replace that 10 years later and so on and so on, add inflation etc.... The other option is cheap lease 2nd hand so the lower lease offsets the higher operating cost of an older aircraft. But then you have to have 2nd hand available and cheap. I am oversimplifying what is a very complicated decision and there is a myriad of options in-between ownership and leasehold, new and old, etc... but the unifying equation involves a lot of cost.
What has happened with QF is that the fleet replacement has been delayed to stump up the balance sheets a few years running. That means there is a reckoning point where it needs to be addressed.