And as an aside, if I look at your list of hype in the final section, I see several things that have either been round before, or where other technology overtook them. 3D cinema is something that comes round about once a generation - the 1920s incarnation failed, the 1950s incarnation failed, the 1980s incarnation failed, and the 2010s incarnation failed. It gets hyped the same ways each time, but nobody seems to learn from the past failure. Additive printing lost out to cheap shipping - why would I own an additive printer that takes 48 hours to do something useful, when I can pay an online retailer similar money to the running cost of such a device to get a better version shipped to me in 24 hours? EInk is an exception - I've seen big EInk displays, but they have no market niche because they're monochrome, slow to update (so not good enough for motion), and too expensive to replace posters and the like due to the expected vandalism rate. The technology's there, the use case isn't. Social TV has happened, but not via dedicated apps - people post online about TV they're watching, and they share spoilers in messaging apps with each other, but it's just not something that's big enough to support dedicated apps when the social media giants support this use case. And hydrogen got beaten out by the lithium battery revolution - lithium battery vehicles are cheaper to build and run than hydrogen, and fill the same niche of low pollution transport powered from renewable energy (hydrogen being generated from electricity was the plan). We also, as a consequence of this shift, have e-assist bicycles and tricycles, which was impractical with hydrogren.