Well it is just a matter of time before ICOs are going to be regulated... Governments care way too much about the taxes they can put on the cryptos to ignore them... with a projection of a 5 TRILLION USD market in 3 years.... those are a lot of money....

To answer your question a government can 'control' a chain with not too many problems, at the end a blockchain is just a self-running database where all data are stored forever... now think about:

• When you buy ETH and BTC via coinbase you have to do your KYC, so CoinBase knows exactly how much crypto you have bought or you are trying to liquidate
• You transfer those coins to an exchange or to another wallet, still quite easy to track you
• The only place I know where you can lose your flow is via shapeshift....
• At that point you can send crypto to a TenX wallet or Xepo and spend the crypto in the real world.... but even there you need the KYC to go above a specific spending limit...

Seems to me there is no way out if you want to avoid it... That's one of the big pro/con of blockchain, everybody know everything if they want to.