Governments and banks want different blockchains. Blockchains that'd make Orwell cry in a corner. Sure we'll get government issues cryptocurrencies: CRYPTOFIAT. All your transactions will be traced, monitored and taxed automatically.
Of course, they'll make exceptions for certain individuals...
I think this would happen if the government see that more people are getting involved with cryptocurrency and in cooperation with banks, they would make a cryptofiat so that they can still track the transaction of the people and would still get their share through taxes. It would actually be much easier for them because all the data are online so there would be no need for them to ask the people to file their taxes because they know how much to collect and might even just send an e-mail to send this amount to that account to pay for taxes. All data are accessible. Compared to what is happening now wherein some people can get away with paying taxes because transactions are anonymous and cash is not easily traceable, cryptofiat would make the job of those in government more efficient.