Walter, the scenario fails because nations don't need to hold $ reserves to trade in oil.

My understanding is that reserves have been held in US$ first because it has been a reliable currency in an uncertain world, and second (if you believe bankers) because the primary theoretical reason for foreign reserves is to protect your own currency by being able to buy it back. If this is true then the best currency for reserves is the one against which it would be worst for your own currency to devalue. Other currency options have appeared- for example, having overcome some of its earlier SNAFUs the Euro isn't a bad choice if you need to keep reserves, though not for European nations obviously ;-) but the US is a massive market with whom many/most countries trade and the $ has made sense as a reserve currency. True? Who knows.

The writers of these articles are correct that if the $ devalues it means the US has had the benefit of goods for which the seller who holds $ is able to receive diminishing value in return, but that's true of any stock or traded item that people choose to hoard. If this is the motive then it's causing people to look for some other form of reserve which has to be an own-goal for the US.