It's been around less than a decade and jury is still out whether it will even succeed or not yet, hence why I wrote "potential". But assuming it does prove sound and reliable over the long term, then its best value is as a hedge against governments screwing up their currency, like Venezuela and other distressed economies. There are already US dollar black markets in those places, and new cryptocurrency black markets are starting to form now too.

As for "unbanked", I don't even know why you mention it unless you're setting up a strawman to knock down. But here, let me do that for you - people who are unbanked don't have access to financial services b/c they don't have money, b/c they live somewhere that economic norms, institutions, and growth all have problems that make it hard to create wealth. Solve those problems and the banks and finserve folks will come running and those people won't be unbanked anymore. But I have yet to see a good case for how cryptocurrency in its current incarnation will solve those problems.