As someone who came through the ranks at a time when a QF cadetship wasn't even an option, I can safely say that it isn't the be all and end all - in fact there are plenty of options out there for those with a sense of adventure. Get out there (yes, even outside Australia) fly some interesting and unusual aircraft types, go to some strips without ILS or 2000m of tarmac, get laid, spend some time away from home and out of your comfort zone, mountain flying, bush flying, tailwheel, skis, floats. Enjoy the journey, have fun, Qantas will still be there...plus you'll have some stories/experiences to share on those long sectors.
Nothing more depressing than a 21 yo already worrying about pension plans and seniority