The coins are just bits on different HDD's somewhere. If that magnetic information dies, bitcoins are lost.
For that to happen, it would require that everyone having the chain stop using the Internet or at minimum the Bitcoin P2P software all together
What you describe isn't the loss of coins, it is the corruption of all copies of the chain and as a result a loss of all bitcoins everywhere simultaneously.
Individual bitcoin loss can occur, it happens when a wallet key is lost. This creates an orphaned wallet that nobody in the world can access, yet contains coins. The coins still exist, they just cannot be reached by anyone