What is wrong with immigrating to Europe / Asia? As an American, if I had many foreign associates that wanted to work for / with me, I would not hesitate to relocate with them to some country that lets us, that would the be US's loss.
But to open the proverbial floodgates is to let entrenched interests win and all the potential startups and growth elsewhere wither and die. It is not like you are going to be founding the next big thing while bound to employment at one of the big three to stay in the country.