Mud Skipper,
I would argue that if Qantas sold Jetstar, or someone else had started a Jetstar-equivalent rather than Qantas, the end is even closer for Qantas mainline...
While sure some routes have been given to Jetstar, I suspect a well capitalised LCC would do/would have done far more damage, far more quickly.
The only solution is to get QFs cost base down - and this is not just wages, it is outdated inflexible work practices, massively inefficient levels of management,, as well as particularly internationally some things to level the playing field - depreciation rates, airport charges and infrastructure etc