It’s a very small niche that can live in one country and earn income in another. Ask yourself if the dollar literally doubled against the British Pound tomorrow, would you choose to live in the UK. It wouldn’t be relevent unless you earned your pay U.S. dollars and paid your mortgage in Sterling. Other than lottery winners and the ultra wealthy, very few jobs can handle a commute like that (but there are some). Retirees from Europe won’t flood the U.S. because they would lose their socialized medical care.