Its difficult to say what is gonna happen with it but I think that the paper money will somehow survives but of course it will be less more used due to the fact that its all gonna be digital.
A lot of banks are already doing great vitalization their money.
but still it will take a very very long time, i think up to now not a 1 percent people of the world are using bitcoin, although people are now taking interest in online shopping but still their number is too low, and i think it will take more that hundred years to replace paper money into digital currency.