I think that only 10% coins/tokens that would be able to survive and will be worth investing in 2021.
There are currently 2400 tokens that are known and many unknown to anyone. By the end of the year 2020, at least 100-200 new tokens will be created. Every day in the world there are 5 new airdrops. I think it is not realistic to calculate. But I'm pretty sure new tokens are being created more than they are being deleted.
But we have to buy only good market capitalization coins. Don't invest money in shit coins.
We have thousand of crypto currency in the market so iwill not agree of 10% In my opinion it's only 1-3% of them will survive for long term. More of them is just a shitcoins that want to grab people's money and no long term plan at all .they are just being manipulated in price because of hype but in the long run they will lost its value and that's proven already from the past altcoin we have before.