Which countries would benefit most from an American brain drain?

Article is built on false premises. Notably citing: "in 2022-24, by our calculations, 20m well-educated people wanted to move there, compared with 14m who preferred Canada (which has a much smaller population). "

Two things: "wanted" and "actively doing so" are worlds apart. Additionally, other countries have about the same or even more complicated immigration rules.

The USA are safe from brain drain. And I'm saying that as a one living in Canada with close friends at McGill University - students still see the USA a primary destination of their interest.