How will the Altcoins die? Is it even possible?
If all market exchange gets rid of a certain coin then it is possible and the said altcoin will soon come to its end. As you know, if a common token gets nearly enough to go into negativity then the possibility to make things worst is probably definite. They will be denied from existing and that's for sure.
90%? it seems like that is too much in my opinion.
But IMO, 90% isn't too much for the solely reason most of those tokens are considered as shitcoins.