If governments banned the on/off ramps to normal currency, then yes it would be effectively neutered. There is an audience that wouldn't care, but it's a small audience.
If I wanted to neutralize it, I would do something like Bait&Switch. Support banks running own cryptos until point where general public will see no difference between BTC and private cryptocurrencies and leave BTC users with their wallets and even when it will remain legal and everything, the "crypto revolution" would be taken by usual suspects (the establishment).
However, I wouldn't like to see it. I prefer world currency to be run by nerds over bankers and politicians.