I don't think so about this point, many altcoins will be forgotten but many altcoins can appear and replace it. As we know everyday appear new altcoins with new project so i think altcoin will be survive in the future.
as in ordinary business, many campaigns close and new ones replace them. this is a common situation and each of us must be prepared for such events and be very adaptable
This is quite possible as many alt coins have come and gone, and its impossible to keep a track of all the alt coins available in the market for a normal investor. The problem with these alt coins is lack of demand, and theyre not easy to sell hence investors are bound to forget them. However I dont agree with the number 99% as popular alts like Ethereum, Lite Coin will always be brought and sold by the investors.