I don't think so that bitcoin will become an world currency. Their are many reason behind this. First of all it is not a global currency because of its decentralised nature it is ban in many developing and developed country. Another reason which creat problem for it is its volatile nature. Its high volatile nature is the main reason behind its falling price and because of this many people consider it as a bubble. Bitcoin run over an complex algorithm and many people still doesn't understand it so they don't believe to use it. So these are some reason behind this topic.