Well, no it does not become impossible. Just print a bunch of money, then the value of the dollars decrease. They get paid their welfare payments, it just isn't worth anything.
If something like that happens, then the United States Dollar will lose its position as the world reserve currency. It will be replaced with the Swiss Franc or the Chinese Yuan, or even the Japanese Yen.
That is based on a concept that one moves and the others don't but actually they all move together.
If we devalue, our goods sell cheaper and we sell more of them. Other countries currency "strong" means their goods are too expensive for the mass markets.
That worked once upon a time for Swiss watches. But it can't be allowed for Chinese or Russian goods. The world is an interlocked economy today.
The imbalance in the economy of different countries because each country is trying to provide themselves with goods of own production not to depend on another country. It turns out that a lot of money spent on it to re-invent the wheel.
Sure, but there always has and always will be an "imbalance." That's okay.