IMO, it doesn't matter if we have national currencies or just one global currency. Eventually currency will be a embedded microchip anyway. That's far worse any day.:-|
Why is that worse, alley? This ‘currency on microchip’ idea is not really all that exotic, we already have that. It is called a credit or a debit card.
Credit cards are now converting from a stripe to a microchip, in Europe they did that years ago. What is the problem with that?