The beauty of crypto currency is that any body can create a coin including the government of a country. The cryto coin can not be treated like the fiat currency because of its protocols. A government coin will be like coins backed by whales. They will have more acceptance by the citizens and other interested people in other part of the whole.
Governments can craete cryptocurrencies as a national money. They have this intention because I remember last G-20 meetings. They will be adapting int the new era of money of course. They won't miss it this time, yet this won't happen instantly.