And you'll put a lot of people out of work in the process.
This is very possible. I'm looking for solutions to what seems like unsolvable problems.
Immigrants are going to immigrate regardless of travel bans and walls. Some will not meet the U.S. requirements to work in their previous home country professions, such as doctor's, lawyers and teachers. In the meantime, they have to find a way to survive plus do what is required to become licensed professioals.
As a side note, some U.S. practicing doctors today got their doctorates at universities in other countries where education is much less expensive, yet just as comprehensive.