The Usbourne Book of The Future, published in 1979, promised us rocket belts by the year 2000. I demand to know where they are!
More interestingly, most of the predictions made for the period 1980-1990 all seem to be happening now, 20-30 years too late.
I loved the quaint prediction of how email might work (predicted for 1991-2000, despite having already existed for a couple of years back in 1979):
Hand-written letters are electronically copied, sent via a satellite link to their destination, where the incoming message is printed out.
Aww, bless! That sort-of did happen, but that was fax-machines and they weren’t really used for letters, only for business documents.