America, UK or others can close their borders all the way they want. Programmer who don't get the Visa won't switch careers, but will be programming in a differ

America, UK or others can close their borders all the way they want. Programmer who don't get the Visa won't switch careers, but will be programming in a different country. As American startup, it's already common to hire people remotely in other country as "contractors". Majority of top 50 Silicon Valley companies has a tech office outside of USA. Continue with closing borders, and center of tech will move somewhere else. Many countries are drooling at having their own Silicon Valley, but American politics treat it as given (same as other areas of American dominance).