That map is carelessly made it could have more dots ,and there are a few dots it shouldn't have.
The Social Security System costs more than all of the bases put together.
There is not a real rule against buying oil with any currency or barter , but you have to have something that the seller wants , dollars work well in spite of some disadvantage.
Yuan are probably a good choice for oil sellers that have other business with China and can buy Chinese product and services , if China is willing to print the Cash and the oil seller has use for it , why not?
This guy seems sort of alarmist, if our Dollars return to the same role in the world that they had in the 60's I think we can adapt. A period of high inflation would be very bad for the holders of debt denominated in Dollars, not the government nor the wage earner.
Oil is one of the very important international trading commodities, but it is not the only one , nor the biggest one.
The US biggest export is the same now as it was in 1700, agricultural products. In 1700 everyone wanted the Spanish coin.