I do not subscribe to the evil monopoly theory.
Firstly, you are talking Qantas Domestic and Jetstar Domestic?
Qantas International has competition, if anything VAI is barely worth mentioning in this regard.
QantasLink has REX
Network has Cobham, Skippers and Alliance.
So regulate them, or force them to sell Jetstar.
Efficient solutions that do not involve propping up inefficient foreign owned businesses with my tax $$