Have always wonder which currency would the world accept if only one currency was to be used. Maybe the dollar?, don't think so, The British won't tolerate that.
Cryptocurrency?. Maybe. Until the advent of cryptocurrency, I never thought that would be possible but it seems possible.
The world is not too far from a unified currency.
Unfortunately, but most likely, there will never be only one currency in the world, and certainly not one that will be accepted by governments all over the world. There can only be a currency accepted by people who exchange it, i.e. Bitcoin or any other cryptocurrency can be such a currency. The one that will be the most convenient, fastest and cheapest will become universal all over the world. I think in the next ten to fifteen years we should find out which cryptocurrency will win this race.