There is a certain lack of specificity in all of those “predictions”.
The only effective response, rounding up and expelling people based on race, creed, and national origin, is so alien to the American Way that I doubt more than 10,000 in the country would have considered it on 9/10.
It would have been an eventual national scandal outdoing the internment of Japanese-Americans (hate hyphenation but it’s the language) during WW2 (oh and certain German- and Italian-Americans too, but so far they and their descendants haven’t turned into a lot of whiny annoyances about it).
OR based on overstaying your visa and/or reviewing Visa applications so that people who don't fill out half of it or put obviously false information don't get approved or, if approved, get immediately revoked!