Over the period of the last 50 years by my specific memory there have been several technologies that have been “just around the corner”. Sadly, they’ve remained will o’ the wisps. They’re still just around the corner today.
The two that leap to my mind are practical quantum computing and practical nuclear fusion. Just a little farther than “just around the corner” would be, say, a cure for cancer. That seems to be farther away now than it did forty years ago.
Can anybody name some other emerging technologies that have just never emerged? Or nominate some emerging technologies that are unlikely actually to emerge?