I definitely expected e-ink to be more prolific, and, when I was younger, I saw this EEG device which was initially marketed at gamers as an alternative control device for computers and for some reason was sure that this was the future, even though a little reading revealed it was pretty impractical.
Google Wave. The way the conversations were threated made more sense. Instead, we eventually got Slack.
Flying cars. There's many YouTube videos of them, but they're not efficient, require designated flight paths, and they're noisy as hell.
VR. Starting with VRML, then Second Life, Occulus Rift,...
I used to think it would take over the world; now I think it won't go much beyond games and sims.
Desktop PCs. (Not laptops, not tablets, not phones, Desktop Personal Computers).
They did, though, for a good while? Like the entire 1980s and 90s?
Somewhat yeah, but they never got to the point I'd have imagined, probably started going south when everything moved away from local processors and into corporate datacenters.