This position has been retained for the past 80 years by both the US and the US currency. This is still the situation right now.

But history is pretty clear on this: power and money change. Currency reserves fluctuate. And assuming that things are different this time would be naive.

Because the rest of the world has faith in the soundness of the currency as well as the strength and reputation of the country issuing it, reserve currencies continue to keep their standing.