In what way do cryptocurrencies coexist with banks? These are completely different systems, and nor they can, nor should coexist.
Cryptocurrencies can and, in fact, are functioning without governmental regulations in many countries, while still remaining at the status of legal (check wiki list for crypto legality by countries), only few impose bans or taxes.
Crypto is more better off without the government, but those greedy people wouldn't want to let the system rest, crypto is decentralised and keeps to the privacy of individuals, government imposing regulations on bitcoin like applying taxes is actually bridging of privacy because there would want to know the transaction going on with a particular address so to be able to know the percentage of tax there will place on it's user, whereas things like this is supposed to be personal.