The youngest 330 is not yet a year old from memory and the 777's are getting older (though nowhere close to old in real terms) so it will be interesting to see which way things go.
You would think, and I know I am applying logic here so it won't actually work in real life, that they would keep the 330's for 10-12 years, unless of course Boeing agrees to pay out the leases, which given their age would be essentially giving them 787's for free, which I can't see happening, given that QF are already an operator (admittedly via JQ at the moment but potentially mainline before too long) and they don't need a lead customer in the region.
The 350, on the other hand, hasn't sold any airframes in these here parts, the closest is, I think, Singapore who are a big customer, so there might be an opening for a deal to be done to get the airframe onto a transpacific operator - but that assumes that this actually means something to Airbus. They may well be selling enough of the machines that they don't give a toss about an operator that is only likely to buy a dozen at most airframes.
The interesting thing will be whether you can retrofit the 242 tonne MTOW to existing late build A330-200's, because if you can the extra 10 or so tonnes of gas would make transpacific in the A330 viable with a decent load. This could see increased frequencies on existing routes or maybe allow the 777 to go and do something else (what I have no idea off the top of my head). BNE-LAX could go to the 330 and the displaced 777's could do additional Sydney frequencies.
Either way, I think there are interesting times ahead!