Paper money will surely be here for a long time and wont be replace by bitcoin or any other digital currency.
When we move on the next phase of our evolution we will not be using paper money.
It will stay for a long time and it will be upgraded by the society and people will contribute a lot of ideas for it. And with the basis that will come from crypto currency. But that's the truth about the future of paper money, it will be possibly gone when people already adopted the technology behind crypto or digital money.