Maybe it's like the internet. There used to be a lot of different websites, and a lot of them were scams. Now there's just a handful of websites, so it's easier for people to understand what to do... And of course there's still a long tail of weird niche sites with new experiments.
The UN recognizes 180 different currencies, by the way. That's 180 different units of accounts, but the amount of forms of money is much larger, and then you have to consider the derivative forms of money, and the various credit systems. It's already an immense, staggering, crazy cornucopia.
I don't think it's realistic that world governments will just eradicate cryptocurrency through legislation. Banking, insurance, finance, the internet itself, all of those things were really chaotic in the beginning, but businesspeople recognized them as useful and transformative, so states didn't want to ban them, even though they were dangerous.
The IMF director is already saying that cryptocurrency will be massively disruptive and that they expect to play a part in regulating the ecosystem and that it's conceivable that the IMF would issue their own cryptocurrency.
https://www.cnbc.com/2017/10/13/bitcoin-get-serious-about-di...
That makes me think it's really unlikely to just go away.