Easy - QF dies, or is forced to do so in a bid to reinvent itself into a shell of an airline. People won't accept that so QF is dead anyway.
Surprised it has not happened already. There's enough cause from previous QR leadership that would like to see QF go the way of Julius Caesar.
No doubt the powers in Australia will try to stop this and QF would of course make an impassioned submission against the idea. Given the media circus that we have had on blocking QR's submissions previously, even if this is far more serious, no one is going to take anyone who is not on QR's side seriously, including the government, the ACCC or the FIRB.
QR-as-VA doesn't have to predatory price as such. They could lower fares to a point that they seem like reasonable prices, especially in lieu of QF ones, and just keep them there, while sporting equal or superior product, which can't be that difficult to do. Give some golden incentives to corporate contracts to switch from Qantas. Add on top of that connections with QR and, with some exceptions due to QR not covering non-stop routes to Asia, basically you have a true QF competitor through and through, except with more financial ammunition to crush and bury the opposition - much more than QF has ever had in its battle against its domestic rivals throughout its history.
Of course, if QF really goes, who cares? That's capitalism.