As per present time many world leaders are thinking to Regulate crypto currencies as on world wide bases and also talking for realesed own country's own Crypto currencies but How can regulated it as on worldwide base 
If we talk about decentralized cryptocurrency i.e. btc it can never be regulated. Since its designed from scratch to remain decentralized i.e. free from regulations. Nobody can control btc at first place. There are fiat form of digital currencies like bnb, usdt, xrp etc. They have nothing to do with cryptocurrency.