Those three countries you grouped together are very different in terms of compensation, quality and volume re: tech companies. Australia leads in all three while quality and volume are an issue in NZ and Canada's compensation vs. the cost of living in its larger cities (Vancouver, Toronto) feels very off.
They are the future ...
Europe and USA will have to rely on in house minds .. which I believe will bring more equilibrium to this world
USA, Europe and Japan are not going anywhere I am not predicting their demise .. just that CANZAU will be the beacon