I don't think paper money will be banned or replaced completely.
Even in the current time where debitcards and creditcards are used worldwide still paper money has a significant use particularly in physical transactions, I think it would still maintain presence even if bitcoin or other internet-based methods go mainstream.
A lot of people that is still using paper money in the future because they dont trust Bitcoin or they dont even know how Bitcoin works.
Bitcoin will be of course more used later in the future and we all also know that it will be more acceptable later, but that wont replace the paper money.
Anything is possible in the future but i personally think that paper money cannot be replaced by any cryptocurrency in the near future.It is fully legal unlike the cryptos which are still illegal in many nations.Most of the common people don't know about the digital expansion and cryptocurrencies and the only medium they have is the paper money.It is used in day to day transactions and cannot be surpassed.