I have enormous respect for Ken, but I think he is largely wrong here. In any dystopian or failed state, why would you want to accept RogoffCoin? or DeLongCoin? Or any of the other ICOs coming down the pike. Yes, there is a space for a blockchain-supported anonymous currency. But the currency that will be adopted will be one that has substantial backing from somewhere—either some large organization with real asset and payments that decides it want to use it (a "cameralist" valuation), or a central focal point (which BitCoin might hold). I can see BitCoin being worth a hundred dollars in the long run because having been first mover is a potential focal point. I can't see anything else having value in the long run. It is not "cryptocurrency coins" that are "lottery tickets that pay off in a dystopian future"; it is (maybe) BitCoin.
After all, the South Sea Company had detected a true market opportunity—there would be durable demand for standardized Gilts. But, as Ken says, "the private sector may innovate, but in due time the government regulates and appropriates": the profits were reaped not by the South Sea Company or any of its competitors but by the British Treasury.
In the meantime, of course, there are Greater Fools for Fools to sell to, and so folly has a chance of looking wise ex post: Kenneth Rogoff: Betting on Dystopia: "The right way to think about cryptocurrency coins is as lottery tickets that pay off in a dystopian future where they are used in rogue and failed states, or perhaps in countries where citizens have already lost all semblance of privacy. That means that cryptocurrencies are not entirely worthless...