Maybe only global space cataclysm or aliens that will destroy all Earth's orbit satellites can force all nodes to stop working. That will mean the total end of blockchain, Bitcoin, Internet etc. But this is an incredible stuff.
According to some reports, about half of all 3000+ altcoin / shitcoin projects ever existed have already failed totally. Some of them have dead blockchains, with no one running the nodes, which is the situation I'm talking about.
Sometimes you'll see exchanges removing a coin due to "broken blockchain". Bittrex does this regularly. I assume this is referring to almost-dead blockchains with no one else running the nodes except the exchange.
