Largely due to our level of debt, China is already trying to relace the dollar as the world's standard:
http://online.wsj.com/article/SB123780272456212885.html
When we begin to default on our debts, which we're in real danger of doing with the current level of government spending, we can kiss the dollar standard goodbye, and with itm our standard of living. We can't print our way out of debt either. Just ask Weimar Germany among others. Citizens were using the currency as wallpaper.
Also, even if they do business here, they may show residence in another country, one that doesn't penalize the affluent. Since the wealthy pay the lion's share of federal taxes, having them leave will greatly reduce our income tax base.