bitcoin may be wildly used by the world or wildly accepted but that doesn't mean it will be the world central currency. you should know that bitcoin is on its own a decentralized currency that is wildly accepted and not a centralized currency. when talking about currency you should be specific weather a digital currency or fiat currency talk. if you talk about digital central world currency then you can talk about bitcoin then the world most common used currency is the US dollar because we cant talk about bitcoin price without equating it with the dollar. that is to tell you how important the dollar is to the whole financial system. there is an impression i always like to correct and that is people always neglecting fiat against bitcoin. let us not forget that our currency is fiat but bitcoin was just invented to be used as an alternative but not a competitive asset. the US will not eve like anyone to rate bitcoin above the USD even if they know the truth.