The 767 is not as efficient as the 787 for obvious reasons. It is not fair to compare the aircraft by airline preferance over aircraft performance. Look at it this way: TOM are looking to fly to destinations such as Honolulu, Vietnam etc. - these would not have been possible with the 767.
As people have mentioned, flying Jetstar doesn't exactly mean moving over from Qantas. What a naive statement. What about EK, SQ, QR, EK, TK, AY or SK?
I think the great hope of the B787 is that you can fly from Origin to Destination without the annoying stop at Transits Stop(s). Now in the case of MAN and Jetstar, it's true that the better option for me as a passenger is clearly a one stop B787 service, competing with the one stop Middle East options. Re-read my point though. Jetstar, specifically is supposed to allow QANTAS to serve markets that mainline can't make money on. Ahh sounds like MAN, I agree. HOWEVER, bear in mind the business model of QANTAS feeding Oneworld at London with the A380. There are strong arguments within companies like this that to justify the immense capital investment in the BigBus and the cost of Oneworld, passengers be funnelled over London. Conversely at the other end, BA passengers on from Sydney have to travel on QANTAS metal. There is a friction between this model and the more direct loco Jetstar option. Hence what marketing at Jetstar see as an opportunity, certain departments within QANTAS will see as a threat.
Addressing your example of Swiss and Lufthansa, they don't really compete, they compliment. Both are full service legacy style (Can't say Swiss is legacy can we?) carriers operating similar fleets in similar markets. Indeed bmi is increasingly seen as the UK arm of Lufthansa as the European members of STAR join closer and closer together.
Personally I wouldn't choose to fly MAN-LHR-pitstop-OZ-final destination in a million years, but you need to be aware that certain people are insisting that the shiny new A380s are filled and Jetstar won't be helping that to happen.
The analogy of the B767 was that it would bypass hubs, exactly in the way the B787 is hyped to do. American launched ORD-MAN bypassing Pan Am's JFK hub and BA's LHR hub along the way. This was the future, a massive European expansion by AA helped to kill Pan Am off. Shoot forward a few decades and the AA European network is a fraction of it's former size and they now fly from their hubs in the US to their hub at LHR and some key European destinations. Even the MAN-ORD is no longer a B767....
The Alliances (not cartels surely) work that way alas. As to what's best for me as a passenger, that's secondary apparently. Forget QANTAS, Emirates is by far a more user friendly option. MAN-DXB-final destination trumps any theoretical MAN-middle east-AU hub-final destination any day. Unless you're Sydney or Melbourne bound, QANTAS is a pain.