I don't think bitcoin will become a world currency, at least in the short term. We all know that bitcoins can be used as a way of payment, but Fiat is still the mainstream way of the world, and it's hard to get a share in the payment field without the support of national policy.
Yeah you have a point. I think it is impossible because as we nowadays money is also one of the identity of a country. Every cointry has different currency so it is really possible that bitcoin can be the currency of the world.
For me its impossible to Bitcoin to be a world currency because country have own currency and also government not allowed it. But possible to Bitcoin to be used a other way as payment, because it is very easy and fast to do transaction. Bitcoin is one of the most reliable coin so using it as payment is good but its better to invest or hold because its value is unstable.