[fennecfoxen]

Governments have given up control before... small governments, where after running their existing currencies into the ground with hyperinflation they adopted the US dollar.

Currencies can only be political instruments up until a point -- and then people get tired of it and start looking for other mediums of exchange, units of account, and stores of value. Bitcoin is theoretically something people could turn to for one or more of those, though it would have to be a pretty bad situation to make Bitcoin's volatility look good.

(Disclaimer. The overall likelihood of this happening at a large scale is not something endorsed by this post.)