The principle of dual circulation and 'bad money driving out good' is formulated as Gresham's Law. While this is typically applied to two currencies pegged by f

The principle of dual circulation and 'bad money driving out good' is formulated as Gresham's Law. While this is typically applied to two currencies pegged by fiat, it would also apply to a pair of circulating currencies in which one is appreciating and the other depreciating. The only problem is that Bitcoin does have an end use—as an anonymous digital currency (c.f. Silk Road). And furthermore, whether you believe it to be 'macroeconomic cancer' or not, it exists and cannot be shut down as a matter of policy.