[ghaff]

I would say Craigslist is definitely a good example. What I think happened there is that the Craigslist business model, such as it was, so thoroughly nuked the profitability of the classifieds space (which was a big part of newspapers' bread and butter for years) that it didn't make sense for a next gen competitor to move in--especially given network effects.

Maybe Ebay? It got away from its roots and is arguably less good for just about everybody concerned than it used to be. But, again, network effects and no one seems much interested in trying to recreate Ebay 1.0 in all its flea market glory.

But, yeah, in general consumer sites that go "OK, it's good enough. We're just going to hang, take long lunch breaks, and keep things going at a just profitable enough level" are going to, sooner or later, be passed by the newer/better/shinier hip kid of the moment.