Australia was not kept afloat by Asian immigration, but by digging up their land and selling pieces of it to China. 30% of Australian exports are to China. More than half of that is coal.
As for immigration, it is much easier to immigrate to the Commonwealth countries than to the United States. They all have point systems for skilled immigration.
It's possible to immigrate into the United States by making a $500,000 investment. But that policy really only captures the upper middle class looking for a backup plan.
I don't know what your definition of "upper middle class" is, but I am pretty sure even in the top 10% of the economy in any given western/industrialized country almost nobody has half a million $ laying around for investment (i.e. that isn't tied up in the homes).
As for immigration, it is much easier to immigrate to the Commonwealth countries than to the United States. They all have point systems for skilled immigration.
It's possible to immigrate into the United States by making a $500,000 investment. But that policy really only captures the upper middle class looking for a backup plan.