The blockchain and its peers are the logical evolution of currencies in the digital era. It had been talked about and researched for a long time. It didn't boom into existence but grew gradually and has been shown to be extremely reliable.
In today's globalised market, I see it as very unlikely that they're going to go down in history as the second tulips bubble. But I could accept that cryptocurrencies are overrated right now, perhaps, as if people had gone crazy and invested all their time and resources into p2p file sharing. It was just another technology.
However, cryptocurrencies solve a strong need in globalisation to be able to trade against the wills of the regional limiters. Governments always want to tax and regulate the daily activities of people. I believe that the blockchain will disrupt these efforts and, in the rise of the age of information technology, will rise as the giver of freedom that people always seek.
In these so favorable waters, I see no chance of the fleet sinking.