What is the exact criteria to become a "dead" coin if I may ask?
Dead blockchain - it is impossible to find nodes to sync the wallet, and there is no reply from the coin dev (project was abandoned).
Also, coins will be removed from the exchange as "dead": In case of the coin developers failure to compensate losses suffered by the users of the exchange as a result of an attack on the blockchain coins, or errors in the coin software.
https://crex24.com/delisting