The U.S. imports far less than it exports; by contrast some countries are very export dependent, for example Germany exports half of what it produces. We export 12% of our GDP and only 6% to places outside of North America. This allows us to have more leverage since the rest of the world needs us more than we need them. This is even more true due to the growth of domestic oil fracking. The result of a trade war would be skewed in the direction of hurting other countries more than the U.S. will be hurt.
The U.S. also attracts more skilled immigrants than other countries (vital to manufacturing the winning new technology). The “Middle Income Trap” theory that democracies are able to grow past a middle level of income and dictatorships can’t is true, in part, because places like the U.S. and Europe are better place to live and work than a kleptocratic dictatorship.  During WWII a key factor for victory was recruiting nuclear scientists from Italy or Germany like Enrico Fermi and Albert Einstein; there was no flow of scientists in the opposite direction.
The U.S. receives the flight capital funds of foreigners seeking safety, we pay them low yields compared to EM countries, and then U.S. financiers reinvest the proceeds into loans at high interest rates to EM countries, thus making a nice profit margin because of the global desire for security, safety, fair play, trustworthiness, transparency.
When global bad times come, the safe haven nature of the U.S. results in the dollar rising compared to other currencies, making it harder for EM countries to repay their dollar denominated loans, thus further enhancing the tendency for EM flight capital to flee EM countries and go into Developed countries.
The EM countries had a great economic output for several decades due to the desire to extract commodities (partly due to an unsustainable China real estate construction boom) and use the cheap labor of EM countries. However, these are low tech industries that are gradually falling behind the new tech as manufactured by the most Developed country economies. International flight capital will continue to leave Developed countries and go to the U.S. Canada, Australia, New Zealand have all had a commodities boom that triggered a real estate bubble which is now bursting. It won’t be wise for foreigners to park funds or buy real estate in those three countries until their cycle bottoms out in a few years. The EU has so many financial problems it seems like an unwise place to invest in. The UK could be fine once Brexit is fully settled.
The nature of China’s economy is that they have a large amount of resources allocated to real estate which remains empty after construction, thus missing out on collecting net rent. After 20 years the compounded missing rent could be more than double the property’s value, assuming a modest appreciation in rent. This could be taxed and used to reduce government debt. In the U.S. landlords rent out their properties and pay tax on the income which the government uses to moderate the size of the federal deficit.
The U.S. has fundamentally a more sound and solvent economy than the rest of the world. This provides a fundamental basis for why the currency has held its value once Volcker tightened in 1979, after an initial period of devaluation during the Bretton Woods exit of 8-15-1971. I expect the dollar to hold up well during the next global recession. It may be accused of being the least dirty shirt in the dirty clothes hamper; since it is the least bad currency then it is the best.