It's all hypothetical unless you have the right to live and work in those countries. Aussies / Kiwis / Europeans can't go work for a US airline because we don't have a green card, same applies in reverse.
A couple of Aussie operators have recently (controversially) gained approval to sponsor some type rated, experienced crew for work visas but that's not a problem that's going to bother you for a number of years obviously. NZ and virtually all European countries are totally closed shop for non citizens.