Nobody has really answered the OP’s question about what happens if governments start a serious attempt to buy up all BTC and destroy them. I mean, if the men-in-black offered someone $Lots, then they may well happily set up an exchange with a good rate and fudge the figures on the front website to make it look genuine. Eventually, the rest of the net might figure out that all coins that had passed through that exchange eventually disappeared but with enough resources they could probably run the exchange for long enough to damage the BTC economy.
Re: How divisible are bitcoins and other market/economic questions
Figures: fergalish