I don't really see this kind of situation coming to reality any time soon. I have always been of the opinion that cryptocurrency has not gotten to that level where we can say that they are going to replace the fiat money that we have in the world. Just for the past few weeks, one of the top cryptocurrency that we have in the world since 2009, bitcoin, has been having a downward spiral and this has been a worry to lots of traders of the coin.
I don't think that any country that is looking at how they are going to make their economy grow from one level to another will like to adopt a cryptocurrency as the substitute to fiat money. In fact, most countries are banning the trading of most of the coins in their areas and this is something that we should think about as well.