dragon man,yes the maths are simple because they're true.If they're not show me and I'll happily accept the correction.The infrastructure you mention is already there.They have the management etc that you talked about.
Check in and ground staff are already cheaper than QF as well as cabin crew and pilots.Although long haul QF have now got qcca cabin crew which are supposed to be as cheap as Jetstar
The difference between the 2 is the cost of the pilots flying to places like Paris.
With the cost difference I can't see us going anywhere new unless it has a viable business class market.Even then I think they would have Jetstar feeder services in Europe connecting with the QF flights out of London and Frankfurt.I hope I'm wrong but the days of us flying to Paris,Athens,Rome,Belgrade and others are a distant memory.