The question "How the cryptos will survive if all government bans it" has been asked often. I think the OP's question is interesting, because it makes us wonder about a hypothetical world where Bitcoin has replaced fiat. What would be the consequences? What would government look like in such a world? How should society adapt?
I've been thinking about a question for a long time... "Isn't it better, if the world accepts Bitcoin and alt coins, while the Fiat currencies system being totally canceled?" It might be a little bit silly, but this question always pop out from my mind
![Roll Eyes](https://bitcointalk.org/Smileys/default/rolleyes.gif)
If you look at the history of Bitcoin, the reason why Satoshi Nakamoto created Bitcoin, you understand it was never meant to be a currency integrated into government. It was a rebellion against government financial policy. The purpose of Bitcoin is to change government, but currently government tries to change Bitcoin.