over time, a lot of coins will disappear
That's what happened in 2017 bull run also. There were many coins which were in top 10 in 2017 but those are not avaible in 2021.
Only the good projects coins will survive long term while rest of the coins will just disappear as no one will buy the shitcoins and there will no demand for them.
Indeed, all investors from those shitcoins turn away because of the long bearish market of altcoins. Fears of missing in out made them out of control of their anxiety, that's why a good project turns out to be shitcoins nowadays. Hopefully, what happened last 2017 will be back this year and so on and new waves of productive project will come our ways then earn more lucky profit soon.