I believe in the words of Jack Dorse, the Twitter CEO, he said: “The world ultimately will have a single currency, the internet will have a single currency. I personally believe that it will be Bitcoin.” I can elaborate on the timeline, stating probably over 10 years, maybe even faster 
That will remain as a dream mate, the world will be having Single currency? lol do you thin China and America will favor to this? 
Bitcoin may become a Universal currency (of course this has been on the run for years) but it is optional to the whole world, because now that china completely taking bitcoin out of their league i think this will be hard to expect this adoption anymore .