Digital currency will absolutely replace paper money as more and more people are choosing to use it instead of traditional money. BTC is on it's way to replacing the USD as the world's reserve currency because it's not backed by any and the Federal Reserve can print money, thus creating fake debt, at their will and loan it out to banks for 0% interest. What a scam of a system, BTC is a decentralized system. Much different.
I do believe in crypto currencies but to replace paper money, it still needs slot of development, on security and usability, it still lacks alot in that area. I use the mother index the not my mother can use it the closer we get, it is because she is not at all technically minded, she has a hard time using online banking. But when we get a user friendly system that secures our funds the bank people needs to look for a new job