No, I don't think so. Sure, there is a lot of buzz around them and they are hailed as the next big thing, yes, but this is almost exclusively due to bitcoins sudden rise and the public becoming more and more aware of it and other cryptocurrencies. Bitcoin is a special case as it's obvious, that a bubble is being formed, which will burst when this sudden influx of new "investors" subsides.
But this is not why I think cryptocurrencies will not substitute real currencies or even hard cash. Cryptocurrencies are not regulated by anyone and far too volatile in their value to be a sound foundation to build an economy around. Economies need stable currencies whose worth either everyone can agree on or is guaranteed by a central authority, so it can be manipulated in times of need or economic voes, even expansions, to bolster external shocks. Cryptocurrencies do not provide this security net. Sure, they are great for individuals, we may even get a digital-only euro, but they can't and won't end any real currencies.