This has already happened. Daraprim (Pyrimethamine) is available today in India for pennies.[1] You can't import it into the United States without breaking the law. The American public should be outraged at the FDA for disallowing drug importation and their overwhelmingly onerous ANDA policy.
[0] https://en.wikipedia.org/wiki/Pyrimethamine
[1] https://www.ibtimes.co.uk/daraprim-like-drug-costs-less-0-07...