I think what Dien predicts is possible if it went unchecked. It isn't any secret that the North American population is on a decline as families are not having as many children as they did years ago.
I think Don's theory is valid as well... but both theories need a little more "rounding out."
The government here in Canada is studying the situation. A declining population means less tax payers -- and we can't have that, you know. So the government is doing studies on supplementing the declining, aging population with immigration.
Their studies show them how many thousands per year they need to bring in. A report by the CBC suggested that if current immigration laws or security laws didn't permit it, then the laws would be changed.
I expect Australia and the US to probably have a similar strategy.
Best Regards,
Steve MacLellan
homebusiness-websites.com