Now that brain drain isn't required to get a great job, we will finally see a diversity of distribution in talent instead of east/west coast. This will be a good thing. It's completely unsustainable to have talent cloistered away forever and always in the same couple spots.
Exposure to smallpox wiped out populations in two continents from no prior exposure. The quoted “not necessarily” isn’t a ringing endorsement. Chickenpox is another example of early exposure/vaccine or very bad things happen.