To the best of my knowledge you have as much chance as anyone else of getting into Qantas, I believe their recruitment process has little to do with age once you have their minimum criteria.
DJ may be a different story. It seems like a bit of an old mates club, or else a "Young up and comers" scene.
Bear in mind there are many more opportunities to fly big equipment these days. NJS, Impulse, Alliance etc will all get you into a jet, REX, Impulse and QF regional into a big turbo prop, and I would not think age would be a big factor there.
You will obviously need substantially more experience than you have at present, so be prepared for the hard yards like we all did.
My advice is the same as to anyone. If you’re trying to choose between flying and another career, choose the other one. If there's NOTHING you want to do but fly, go for it!! Whatever you end up flying will have a higher service ceiling than a desk!!!
Blue skies