That's what I always ask those Texans who are so eager to secede. Do they plan to deport their 3.2m Medicare recipients back to the USA?
Most Latin Countries have very good medical care, cheap. However that may not always be true. Americans can buy an insurance plan before leaving the country. All countries do not have cheap medical care.
My supplemental Insurance gives $50,000 of care for out of the country expenses, when Medicare does not pay. That does not cover a move, only a vacation.