Earlier quoted context omitted.
This will be true right up until the point it is not. The US dollar dominance is not a feature of the universe, it's a social agreement that, like any such agreement, will eventually come undone.
Not to sound hyperbolic but I feel once the US Dollar crashes entirely to the degree that it no longer serves as a "default currency" of sorts, that society will have broken down far enough that even the gold will be relatively worthless and the predominant goods of choice will be cans of dog food and beans.
For a year you will be correct. However after a year what is left will start to rebuild, and gold works better than beans (remember the cans are all eaten by now - we are talking beans someone actually grew). The problem with beans is they spoil (even carefully stored): eventually someone says "I have all the beans I need now, but I still want to sell my shoes". Using something like gold as an agreed medium of exchanges means the bean grower and shoe maker can make an exchange without trying to put together a complex trade involving a dozen people just to get enough of various goods to satisfy the show maker. Instead the shoemaker can get some gold and then buy everything as an individual transaction - and the people he buys from can in turn go to the bean grower if they want beans.