Duncan Niederauer, CEO of NYSE Euronext, answers the question this way in the latest Business Week:

The initial sense we’re getting?and we plan to survey our listed companies in the coming days to get a more accurate read?is that these companies will find ways to cut expenses to compensate for this increase in taxation, and that will probably be largely in the form of jobs. And companies might continue to be headquartered in the U.S. but would perhaps incorporate in another G-20 jurisdiction. [Emphasis added.]

Niederauer?s comments responded to news that the Obama administration plans to crack down on tax havens.