[guareber]

I'll give one counterpoint:

When did you see anyone on TV mention Digg?

Reddit's become mainstream, it's quoted by serious news outlets, joked around on Last Week Tonight (and other politic joke shows), and I'd say it's as likely to disappear as Facebook. Which is to say, surely but very slowly.

[Kye]

I'm sure I saw a mention once or twice on TechTV and/or G4, but that just supports your point.

[ilikecakeandpie]

They got a huge boost from Stephen Colbert mentioning them