I think what people need to realize about cryptocurrencies is that they aren't going to derive their value from being convertible to fiat currency.
Rather cryptocurrencies are going to be revolutionary in the sense of how they can be combined with other technologies.
For example, what if World of Warcraft used a cryptocurrency based system for ingame currency? Where the ingame money was actually finite and that in theory the players in the game could suffer from an economic depression. Or a few players could hoard all the wealth in the game. etc. etc.
The game would be way different than it is now, which is to say that it just emulates an economy, not actually implements one.
This is probably a bad example to get what I am trying to say. So lets imagine a different scenario. Let's say we wanted to build a social network, where we didn't actually want everybody to just be able to say whatever they want without a threat of consequence. What we want is a social network where you have to do something to earn the ability to speak, and once you speak you lose the currency to be able to speak again until you do something once again to earn the ability to speak.
What you have to do in order to earn the ability to act depends on the service in question, but the same basic concept of a cryptocurrency is what underlying the system. In that the platform only has value when the ability to act is a limited and highly valued resource.