Stablecoins enable the United States to extend its currency area to other countries without printing paper money, thereby also exporting its inflation. This works as long as the local currencies are weaker than the US dollar. It has only a temporal effect on the end of the US dollar. That end, however, is inevitable. If people actually begin exchanging their stablecoins for Bitcoin because they need a reliable store of value, there will be a supply shock. Then everything will happen very quickly.