WhoFlungDung et al.....
Empires have been lost in the past because the generals kept fighting the way they did in the last war, rather than adapting to the best way to fight the next one. I wouldn't want your way of thinking to be in the mind of any general I was following into battle.
The world started changing 30-ish years ago with Freddie Laker on one side of the Atlantic, Southwest on the other and the Airline Deregulation Act presented to Congress in Washington in the middle. Price driven markets, low fares, secondary airports, removal of barriers to entry, low costs, outsourcing etc etc started to become the watchwords of the industry. many player just "never got it" to use your anti-Jetstar words Mr WhoFlungDung.
Braniff, TWA, Eastern, Northeast, Reno Air, People Express, Western, Republic, PanAm.....didn't get it somehow or another. Some didn't manage the full service model, some didn't manage the low cost model. Doesn't matter whether their management were cruel, evil or wonderful...they're gone. And probably one of United, Delta, USAir or America West will yet go down the tubes.
If there was even one chance in 20 that someone other than Qantas would start a Jetstar style operation here then the Qantas Board had no choice but to be pro-active and do it themselves, to get their share of the expanding low fare market and to fend off other trying to do the same thing.
If the likes of the Jet Blue founder had started a Jetstar operation here, independent of Qantas and as a competitor, then Qantas would by now have folded up its domestic operation except for maybe MEL-SYD-BNE and if SIA ever got onto the Pacific, it would have folded a large chunk of their international operation as well.
Your future rests on the fact that the Group has managed that most difficult of balancing acts in the two brand strategy. It matters not that in being the repository of QF's loss making routes and defender of mainline yields, Jetstar is subsidizing mainline. That's just a normal part of business. JQ's reward is very rapid growth, quick promotions and of course the 787.
To even contemplate the "Do nothing" option for mainline would be to invite in the receivers. There was one and one only viable battle plan and it has worked.