My idea for a government would be to build a secret mining farm, that perhaps could net them 10% hash rate, but to leave that offline. They then make a pool that gives them 15% of other users hash rate. Then they simultanoeusly turn on their farm and attack the current largest 3 pools; remember just preventing the pools accessing the blockchain for a few hours would be enough to cripple the network and cause a sell off. In terms of miners moving hashing power, if the top 3 pools were intermittently able to access the block-chain, where would they move to? How would they know which pools were reliable at any moment?

In any case even if we dont agree, at least it gave me an opportunity to give you an upvote for a carefuly considered post :)