I second this idea. If at some point the gov't becomes convinced bit coin is viable, they could just start their own new block chain . If they bless it with some sort of official "approval" (e.g. Their coin is legal tender for taxes), then that one can supplant any other. And as the parent comment mentioned, any sufficiently large market force can do the same. Eventually, bitcoin won't be the only crypto coin. And if the gov't can create its own competing coin, it can create two, or N, new block chains. thus, it can mint crypto currency just as with fiat money.