The US seems to have a monopoly on the ability to pay top talent (at least in the west).
At the high end of the talent pool, I don't think opening up is going to have a significant impact. We're mostly already internationally mobile or can demand competitive salaries, and a new supply of mid-tier talent will only create more capital-deploying opportunities.
I'm a computer vision person with a good grasp on 3d geometry, SLAM, linear algebra, statistics, filtering, etc.
We've had budget and I've been trying to hire another me for at least half a year with no luck (western Europe). Thousands of applicants and the couple of interesting candidates were snapped up before we could move (and likely for more than we could pay).
I'm about to leave and go on the job market, and I have no concerns whatsoever about landing a high paying job. It also helps that I have ties to the bay area and am more than willing to go back.