Fun thought, but honestly I doubt it. It would be nice if we could get a world entirely of decentralized currency each with its own unique trade value for use on different values of objects, but there will probably always be people too attached to currencies backed by banks and governments - you know, the sort of things that most people who don't look into it too deeply feel are "concrete" enough to be trustworthy - for them to ever go away. It'd probably be more likely that we'd eventually get a "world currency" backed by a community of nations, something like a Euro with larger reach or what USD often ends up being, for those types of people to continue to use. And since it'd be viewed as "universal" it'd probably still be the currency of choice for global commerce.

It is a fun dream, though. Buy your lunch in Pascal, pay for your Netflix in Sia, pay your rent in Ether, and buy your car with a Bitcoin. There's something vaguely cyberpunk about that vision, and I've always felt that our world is lurching slowly towards a cyberpunkian future.