I think bitcoin could be a one world currency as much as that might alarm conspiracy theorists. As long as it's decentralized and not issued by a one world government then it's fine by me.
There would be nothing wrong with bitcoin being some sort of universal currency. In fact, I think it would be very good as one and hope it happens. It's not like you need to speak a specific language to use it as it's all math based and any person can use it across the globe.