True, Trump 1.0 said he’d cut off any country that didn’t take them back. He didn’t (e.g., India and China). Obviously Biden doesn’t either. What is future of this?
The future of this is probably like Bill Clinton's modest middle class tax cut. That was a campaign promise. Addressing the nation as President, he bit his lip and said he tried, he never tried so hard to do something, but he just can't. And that was the end of the modest middle class tax cut that was never going to happen.
The most realistic scenario if the government became determined to get rid of as many as possible would be self-deportation, i.e. they just leave on their own. They could be encouraged to do that by cutting off all benefits, especially work permits and anything the government pays for. The government always has ways to make people miserable.