Also, I think the US will have something similar in reverse: Some of the brightest people educated in the US are going back to their home countries because they have visa troubles, social problems or simply better opportunities due to simple things like housing or structural things like the industry moved there.
Also, judging by the enormous hate stream on the social media, many can be nudged to move out of the US to have some piece of mind. After Brexit, many EU citizens choose not to stay in UK even if they had that option because they have become a political subject and since they are not desperate why stay and risk it?
China appear to be the next frontrunner in this. Many times, if you venture outside of the angloshpere you find out that somewhere(often in China) somebody is already doing it at the same level or better.
There probably is going to be a correction at valuations. Cool stuff is happening in China and elsewhere and the USA is in a disarray with idelogies so extreme that are not too far of from the stuff that ruined Europe in the first half of the 1900s. Coup attempts, assassination attempts, election denial, mainstream targeting of group of people, rich looking into capitalising on all that when social disparity is so large that some live like kings others teetering - this is not a healthy society.