No government would be able to control the BTC money supply. To have that level of control would be like controlling the internet.
Government doesn't need to control Bitcoin on the technological level. That's exactly my point. All the govmt needs to do is make sure BTC holders have more wealth when forking to altered bitcoin sources and giving up decentralization. No majority will reject personal benefit (or the smaller loss) just for ideology.
Upon a hard fork that you suggest the Bitcoin holders at that time get BOTH. The pre fork coins can be used and spend on both blockchains. Get it now? So if the goobermint forces a blockchain fork I would be very excited. I get to keep, use, horde the original Bitcoins and I get an equal number of UnCoins to do whatever the hell I want to with, including selling them to the UnCoin backers like you in order to increase my real Bitcoin holdings.
I say quit talking about it and fork the chain already. If/When they do it will be a happy day for all Bitcoin supporters!