I'm not sure that bitcoin will replace Dollar Soon. the government will verify, analyze & discuss hardly with the parlement before take an important decision. cause it effects to the economy, politic of the country.
Yup. There are factors that run the current fiat market that would greatly be affected if btc takes over. I don't think banks and governments would allow that to happen unless they have full control over btc, which is unlikely to happen.
The bad news for governments is that to take full control of all cryptos is impossible but there is a possibility however small that bitcoin can take over the world economy especially f they keep making as many mistakes as they keep making, if another economic crisis strikes bitcoin is going to gain a lot of adopters.
That chance for bitcoin to take over the world is not high because a lot of governments hated for having a decentralization in their country so if they want to really do something against the cryptocurrencies then they can do it to just have a regulated currency and take a small control out of it.