That's what I have been wondering about. You tie their economies to a currency that fluctuates as wildly as BTC does.
I don't think that any of the top 30 strongest economies will ever replace their currency by BTC. That confirms that there is no advantage at all in changing to BTC.
There are now already about 15,000 different crypto's. The last year alone about 5,000 new crypto's were introduced. There will be more different crypto's then there are currencies in the world.