I'm all for cryptocurrency but this idea has always unnerved me, quite alot. The reason why I like cryptocurrency is because its free from manipulation by banks and government but at the same time if the world has only one currency it would be easier to manipulate humans as a whole.
But if so many currencies are present, is it good? If there is not a key currency, I think the market will be diluted, and the development will slow down, or even lose.