Edit: down voting this does not change the facts of life.
Courts have more power than crypto enthusiasts/crypto promoters/pump and dump peddlers/etc. That power is enforced by Guys With Guns.
That's why GBP was very valuable when Britain was the big dog on a block, US dollar is highly valued now and currency of Venezuela is in a toilet.
Decentralized nature of the crypto-currency is something that will destroy its value as there would be no one to beat the living shit out of the Punk Joe on a behalf of Aunt Suzi or US Navy showing up next door.
Where I do think we would see block chain applied is international settlements between central banks. Imagine, if you will, that all money flows between all countries in the aggregate would be visible and validatable by all central banks. Considering that we are rapidly approaching the end of the anonymity of inter-country banking it seems that those book-to-book transactions would gain a lot of additional legitimacy if Egypt CB could verify that the money moved from Sweden did not come from Israel CB if Egypt's position is not to accept Israeli' money.
And in any case, most of the people involved aren't anonymous, in practice.
An asset is an asset.
If you buy and sell something with cash - well - you have to tell the taxman, and possibly the SEC if you're doing something they should know about.