I have to admit, I've always wondered what would happen if say, the old Twitter staff had just completely wiped the servers before they left. Would they even try to bring the site back, or just write off the whole company?

But seriously, a network effect isn't necessarily the end of the industry. Lots of sites and services make major screw ups that drive away a lot of users to an alternative in some way or another, or outcompete a huge incumbent. Like what happened with Digg and Reddit.

Digg was sold to someone that didn't understand the internet, and it was not social, so it was just like HN - not a place to put your "page" down and have your friends follow you there.

Reddit is a bit different - but as far as the data is concerned it has not once dropped in usage and is about double what it was a couple years ago.