I want to note that when Brexit happened EU citizens had about 2 years period to move to UK and just like that get their full rights there and those with enough years of stay had the right to obtain British citizenship. Streamlined process through scanning your id using an app, little to no hassle.
IIRC half of the EU citizens left despite having all those rights and streamlined bureaucracy. My observation was that those desperate or those who ware having their perfect life stayed, those who had other options left UK because it wasn't worth the stress and you future being bargaining chips for politicians.
I bet you, if this continues for some more time USA will no longer receive the best and the brightest. Those have options and their parents will prefer the options where their golden kids don't risk being subject to life changing actions or even abuse.