In the world of hardware:<p>S-100 was going to be replaced by VMEbus, then the PC came along, then the ISA bus was going to be replaced by the PS/2 bus, but it was too much lock-in, so we got EISA instead.<p>Laptops had expansion ports, using the PCMCIA interface, we called it People Can't Memorize, Computer Industry Acronyms<p>Bubble memory was supposed to make rotating disk obsolete.
WORM (write once, read many) drives were supposed to revolutionize backups<p>Back in the early days of transistors they weren't as reliable as tubes, Magnetic Logic used ferrite cores to do logic, and computers were built out of it.<p>MMIC logic, where a cantilever is etched in free space, and static voltage is used to move it between contacts, could have been amazing fast, low power logic, but it didn't work out<p>ISDN - Integrated Services Digital Network, as going to be the ultimate connectivity, until the phone networks decided it meant "I Smell Dollars Now", and eventually it became "I Still Don't kNow"<p>ATM - Asynchronous Transfer Mode was going to revolutionize the phone networks, but eventually it was replaced by IP.<p>In the world of software:<p>P-code was the first cross platform interpreter, then Oak/Java, then .NET/Mono, now WASM<p>In leu of actual capability based security, we got VMs then Containers, now we're getting WASM<p>The Semantic Web was going to have all of us manually give context and labels to our web pages.<p>Fuzzy logic was a thing way before neural nets<p>As were "expert systems", which were going to automate away most professional jobs<p>Lots of things come and go, this industry is way more fashion driven than most people realize.