There was a stat here from a while back saying that half of all Silicon Valley startups were founded/co-founded by immigrants. There was another saying that all net job growth in the US in the last ~30 years was because of growth in the small/medium business sector.
So while it would take some time to see the results, and the casual factors probably not be put down to immigrants leaving (or being denied/not applying to enter the US to begin with), you would see an eventual impact on job creation and economic growth.
Perhaps the slow recovery after the 2007 crisis could be partially put down to the post-9/11 paranoia and making it more difficult for smart people to enter the US? It's total speculation on my part (something that occurred to me as I typed this comment), but an interesting idea nonetheless.
I have no doubt whatsoever that it will have a serious impact on America's economy, and I will be the first to agree that we deserve it. A shake-up will be healthy (maybe I'm a closet Trotskyist after all).
What I'm saying is that it will make no difference whatsoever in a free-market sense, because the free market presumes perfect information. The reduction in America's fortunes will never be ascribed to our lousy immigration policy - in fact, quite the opposite. It will be used to justify even worse policy. As is, in fact, happening right now.
So while it's nice to think "That'll show them," it won't actually show them. We're the country that originated Hollywood. We're really good at lying to ourselves and each other.
Also, America was on top because the Economist arbitrary invented a couple of metrics like "yawn factor" to put it there. Stupidest damn article I've ever seen. Come to the Rust Belt; I'll show you where it's not a good place to be born. In fact, if your parents make less than about $400K a year, you're better off in any industrialized country in the world.
So while it would take some time to see the results, and the casual factors probably not be put down to immigrants leaving (or being denied/not applying to enter the US to begin with), you would see an eventual impact on job creation and economic growth.
Perhaps the slow recovery after the 2007 crisis could be partially put down to the post-9/11 paranoia and making it more difficult for smart people to enter the US? It's total speculation on my part (something that occurred to me as I typed this comment), but an interesting idea nonetheless.
Also, the Economist published a list of best countries to be born in: http://www.economist.com/news/21566430-where-be-born-2013-lo...
The US is 16th, behind Australia, Canada, and many European countries. Years ago America was on top.