WebTV -> YouTube, Netflix. VR -> Warcraft, EVE Online, Minecraft. PDAs -> iOS, Android. P2P -> Spotify, Skype, BitTorrent. Enterprise Software -> A lot, but obviously not well known, say Atlassian. Semantiv Web and APIs have largely failed, probably because of the shift to mobile. Casual games -> Rovio, Supercell, King. Microblog -> Tumblr, Instagram, Vine, Twitter. Embeddable widgets -> All the big companies. Failed dot com things -> "sharing economy" and of course earlier things like Amazon.
And most of those things are still successors to other technologies that performed the same function.
Most of the things happend, just as we know wearables, IoT and AI is going to happen. It's when and how that is the question. The people who hype things are always going to dominate over the people who argue the facts, at least in public forums. Look at any discussion on HN about space, self-driving cars, digital currency etc.