The blockchain hype seems to have some parallels to the Second Life[1] one. The technology isn't quite there, the valuations are immense, and it all seems like a real life implementation of a Neal Stephenson novel. Second Life doesn't seem to have gone anywhere but it doesn't mean cryptocurrencies won't as well. From the outside they do look just as niche and generally lacking in use cases.
[1] https://en.wikipedia.org/wiki/Second_Life