what if the government closes or does not allow the exchange of Bitcoin or cryptocurrencies with the official currency in each country? 
If that happens, then all cryptocurrencies die too, not just Bitcoin. If Bitcoin is banned, but other cryptos get permission, then we can exchange Bitcoins for other cryptos, then exchange them to Fiat. But can the government do it? I sure don't. Because the existence of crypto is now a necessity, and a solution in the midst of difficult transactions at the international level. The existence of crypto is not to fight fiat.