If there are no nodes then coins can't be transferred so the coin could be considered dead. But if nodes came back and coins could be transferred again (highly unlikely) then the coin could be raised from the dead.

Without liquidity a coin is dead. It doesn't need to be on exchanges, people can still trade OTC, etc. but if no one wants to trade anything for it, regardless of nodes, it's dead.

People have to take interest but those people create the above two things, so... No people = dead.