Thinking more about the theoretical vulnerabilities of cryptocurrencies, the governments of the world could block the exchange servers from accessing the internet backbones (it is known that all major backbones have physical backdoors owned by the NSA etc.) - not even VPN etc would help in this situation. The value of the currencies would collapse which is another reason why decentralized exchanges will be made - no central point of attack.
If the exchange website is optimized well enough(images,js,css on CDN) it can be feed with one home internet account (bandwidth) on many places on earth using TOR for example. I dont think any government can act against progress. I think the reality is that politics try to adapt rather than go against... thats their everyday job - to adapt. I am talking for eu... in US there is chance for thinking about crashing crypto world. No other country politics and bankers can think about this as reality except US.