Future remains intact of the paper money as worldwide there cannot be one currency. Paper money will not disappear anytime soon, maybe it will be replaced by something else similar to paper. Bitcoin could act as an secondary currency if country adopts it.
I think the paper money will not be replaced by other banknotes version but will be replaced by something more sophisticated like digital currency. perhaps currencies like bitcoin could take over
Bitcoin has all the potential to replace paper money. But the question is what is the level of understanding about bitcoin by people and how many people from around the globe are having awareness on bitcoin payment system. Without any proper answers for above questions, it is highly insane if we are expecting bitcoin to replace paper money.
Bitcoin is actually not that popular, some of the users of bitcoins are from the major countries only like USA, EUROPE, and CHINA. If we want to see bitcoin to be a popular global currency we also need to see some countries adopting with bitcoins.