According to Coinmarketcap.com, 1620 kinds of the cryptocurrencies in total are being traded as of today. The market capitalization is US$280 trillion.
Having said it, I have to ask a very simple and fundamental question to cryptocurrency enthusiasts: Are they self-sustainable? Can anyone answer?
There was a paper about self-destructiveness of the cryptocurrencies with the “long chain” rule. (https://arxiv.org/abs/1405.0534)
I am afraid the self-destructiveness applies not only to the ones with the long-chain rule but also to most of them simply because they are NOT designed to be self-sustainable. (I am almost certain that none of them are not.)
Now we at EcoVerse team is designing a cryptocurrency platform with self-sustainability. The whitepaper will be released soon.