Well, OP, that's what we kind of have now. Everyone's using bitcoin (apart from other alt-coins), so I'd say that it's being used globally.
But, if you mean that one and only one crypto will be used, then the answer is no. Creating your own crypto is easy nowdays and everyone can do it. Also, countries are developing their own.
The way I see it playing out is:
- all countries will have their own crypto, backed by fiat
- various cryptos will be used in various businesses they're designed for. One coin for one business.
- they'll probably become something of a token. Something like what steam has, but you'd be buying crypto instead of dealing with fiat on their platform
p.s. also what you're referring to is somewhat close to NWO