Those delisted Altcoin in exchange site will effect to decreased the volume and delisting happen because of no demand in the market or the project not yet issue some plan to their project that resulting to be delist but dont worry I'm sure those altcoin that delisted in top exchange site have listed in some decentralized or centralized exchange site.
Some of these exchanges are the problem we are having in this cryptocurrency industries because they are not holy too when it comes to scam, in the first instance, what is the essence of registering a project they know they will eventually delist, why didn’t they do their due diligent first and be sure that such project is a quality one and will stand the test of time before delisting them.
Most of these projects being delisted by them are not because they moved to decentralized exchange or another centralized exchange, majority is because they have turned to shitcoins, why few are the ones that can no longer make payment for their services.