Perhaps one day with the current bitcoin advances, bitcoin digital currencies will be an international currency for all countries, and make it easier for every human to make transactions between countries when going to another country.
if it happens in the future it will certainly affect the paper money that exists around the world, whereas we know when the banknotes have a lot of history and symbolize the diversity of a country with other countries.
if that happens, surely the government will not remain silent on the matter, there will be an agreement between state governments to immediately close the bitcoin network to the world.
what will you do if you have a lot of bitcoin.
What you're suggesting is probably never going to happen.
The worldwide regulation of bitcoin may occur, and in fact, the process is already starting to get underway. However, the worldwide ban of bitcoin is simply something that will never happen. It'll cause public outrage, and will be completely ineffective.
For as long as people see a reason to use bitcoin, and there always will be as long as fiat is still in existence, bitcoin will survive. Bitcoin is decentralised. People will simply trade peer to peer instead of on regulated exchanges, just as we see in countries with exchange bans already. But again, these are very extremely circumstances that will never happen.