People create opportunities. So any abrupt changes in migration and immigration flows and patterns matters a great deal. Many studies have shown that highly educated immigrants have a higher likelihood of starting new business ventures then the general population at large, so immigrant influx into Canada and the USA are critical in maintaining a global competitive edge. Immigrant entrepreneurs where largely responsible for many of the startups in Silicon Valley.
So it’s disturbing to see a study  that reports that immigrants with advance education are increasingly likely to return home after taking advanced degrees in the US, leaving the country that trained them facing potential skills shortages and increased competition. This bodes well for emerging markets but not for western developed economies. “A combination of changing perceptions about where opportunity lies, rising nationalist sentiment in the face of a global recession, and poorly thought-out immigration policies, is said to have caused the shift in sentiment and behavior” observe researchers. Among the other reasons given for leaving the U.S.were better economic opportunities at home, a desire to be with friends and family, and concerns about job prospects and the availability of visas
Data also supports that the same is happening with foreign students studying in Europe. Researchers see a fair amount of returnees from Europe, attracted back to China and India due to the opportunities in their home countries. If countries do not provide an innovation-friendly overall environment, where highly skilled workers can use, create and disseminate knowledge, then attracting more workers might not lead to better innovation and economic growth outcomes anyway.
In October 2008, the above researchers  polled 1,224 foreign nationals from Facebook, who were either studying in U.S. institutions of higher learning, or recent graduates. They found that only 25% of Indian students, 9% of European students and 7% of Chinese students, thought the best days for the American economy lay ahead. More significantly, 74% of Chinese students and 86% of Indian students felt the best days for their home country's economies lay ahead.
Other disturbing results for America showed that only 6% of Indian, 10% of Chinese and 15% of Europeans intended to settle permanently in the United States. The number of graduates who wanted to stay in the U.S.for a few years also fell, with only 58% of Indian, 54% of Chinese and 40% of European students wanting to stay on. Earlier National Science Foundation research showed that 92% of Chinese students and 85% for Indian students stayed for five years or more. 
The students polled were also more of an entrepreneurial group; 64% of Indian, 66% of European and 68% of Chinese students said they wanted to start a business in the next decade, with most of the Indian and Chinese students hoping to do so in their home countries.
[1} Losing the World's Best and Brightest: America's New Immigrant Entrepreneurs, Part V, a study sponsored by the Ewing Marion Kauffman Foundation
**An excerpt From the soon-to-be-released book -Hard Times, Golden Opportunites by Walter Derzko; publisher-J Wiley and Sons