I don't know in the last step of Bitcoin everyone will only use it and no any other currency will exist again. So I like to hear from some Biblical Scholars in the forum to tell me more on this topic. This thing that I said is inside the Holy Bible but I can't recall the scripture but it is in the book of "Revelation".
The US dollar is widely accepted. Far accepted than bitcoin. What's to say that isn't the one currency you're talking about. Bitcoin isn't accepted nor is it used by the whole world and even if it is adopted by every nation later in the future, bitcoin is most likely not your one currency that the Bible talked about.
I think if such a currency would exist and to be used as a world currency, don't you think the currency would be in paper form.