I am 100% sure that digital money as cryptocurrencies are going to displace physical currencies, but it is a distant future. In my opinion, such future digital money could be based on cryptocurrencies ideas, and maybe even on a blockchain technology, but future money will look different from what we live through today - different world, different rules. And like it was said before in this thread, even right now we have an amazing example of cryptocurrencies being used as a regular money - we've got ATMs, online shopping in more and more places can be done with cryptocurrencies like Bitcoin, Ethereum, Dash or (mentioned here before) FuturoCoin, which is still a small cryptocurrency. Recently I've found an
article about it and you can already pay with FTO for example, in a restaurant.