Even before the $10-20k deposit, visitors from many of the (presumably impacted) countries already face some ridiculous barriers when applying for a B visitor visa. Wait times for a visa appointment are typically 6+ months, and costs include several hundred $ in nonrefundable fees.
Aaron Reichlin-MelnickNEW: The State Department finalized a rule implementing a "visa bond" program for tourist/business visitor visas, to be imposed on a list of countries to be announced. Applicants for B1/B2 visas from those countries will have to pay a $10k, $15k, or $20k bond, to be paid back once the visa expires.