This keeps me coming back to the need for some kind of open standard peer to peer money payment system. Something that can't be gamed or defrauded due to the use of strong encryption and public/private keys.
What would back such a currency? No clue.
What would fed.gov do? Crack down hard, of course. If such a system got off the ground, it could mean the end of the nation state, at least in a financial sense.
Between strong encryption, and game theory, I think the technical side could be worked out. The political and economic side of it is the tough, probably impossible part. The net result would be some sort of crazy digital minarchy/anarchy if it took off though.