As an American I can tell you that it's better to just beat that dead dog. Well, horse really. Elephant. It's definitely an elephant. Now get out your flail and go to town at that bitch. And continue the beatings until the problem is resolved.
I know, but I didn't want to have to explain two different sayings instead of just one. At least, that was my thinking when I wrote that comment at 3am.
Serious question:
If the american health care system (which may be the most prominent thing stopping migration currently) would become a socialized-financed commodity how much %GDP would America loose?
Probably none, because the people wouldn't go bankrupt because of a broken leg and be able to spend the money and be able to keep spending money on something worthwhile instead. Breaking people's necks financially by means of medical bills is not a great thing in the long run for the economy.
The current healthcare is a net loss for the country. The only people losing money would be private medical industry, and its share holders, but it wouldn't off set the losses caused by the crushing expenses, and bankruptcies as far as the general GDP is concerned.