First, you read lots of science fiction. This tells you what to expect in, say, 30 years. Consider the number of Star Trek 'predictions' that arrived in the lifetimes of most of the kids watching the show. Scriptwriters 'just make this stuff up' as dramatic devices, often recognizing a need far in advance of the technology portfolio required to carry it out.
Second, you pay attention to trade magazines in various industries. These could include electronics, nanotechnology, biotechnology, science, and other topics relating to engineering. In doing so, you read about things 'you've never heard of'. Some of these will eventually percolate into the computing environment - lithium-ion batteries, OLED screens, and MEMS accelerometers all made the current generation of smart phones possible.
If you actually do these things, then you can bring the interviewer up to speed on some 'neat stuff'. This is even more persuasive if you have websites show them for reference. One or two of those, and they'll either be happy or overwhelmed.
As an interviewer, what I'm (personally) looking for is someone that isn't going to get blindsided. In the late 1980s/mid-1990s I was reading in the media of thousands of mainframe programmers let go because their skills were 'obsolete'. My BS detector was buzzing off the wall - programmers are programmers. They learn languages. If you couldn't keep a programming job in a company that was transitioning, you couldn't keep a job as a programmer of any kind. Something else was going on.