Perhaps I'm just tired of waiting for my flying car or hoverboard, but I'm not so optimistic that we'll see certain technologies become popular.
- Cars that drive themselves. There's lots of research and good arguments about safety and efficiency and congestion. There are already commercial products for parallel parking, distance-controlled cruise control, and lane detection. But I think the real problem is liability. If there's an accident with a car you drive, it's a local problem (you). If a big company's car crashes while driving automatically, there's the potential for a very large lawsuit. Society benefits from automated driving but these companies pay for it. Early adopter individuals don't benefit enough that the companies can charge more. Such an arrangement makes it much less likely that these systems will leave the research phase. I also think congestion is much more likely to be addressed by variable pricing and better information than by automated driving.
- 3D displays. There's been a recent increase in 3D TV, movies, and video games, but most of the technology doesn't seem any better than the last time 3D flared up in popularity. The image in your eye is inherently 2 dimensional. If it were 3 dimensional you'd be able to see behind and inside things (Flatland is an interesting read if you want to understand this better). To see 3D in your brain you need to have separate images in the left and right eye. You can do this with glasses: color filters (red/blue, used for TV), circular polarized light filters (used in movie theaters), or timed shutters (used in video games). Or you can do this without glasses, by using the difference in viewing angle between the eyes (Philips WowVX for example), but this requires either a single viewer or all viewers to be roughly the same distance from the display. You can also produce 3D effects at a different level of the brain, by viewing different angles (either statically with animation or dynamically with head tracking). The problem is that all of these systems have limitations that exceed the marginal benefit of 3D, once the novelty wears off. So they'll all be used in specialized situations like medical imagery, advertising in malls, and a small number of TV/movie/game applications. But I think 3D displays are not going to be widespread.
- Humanoid robots. Humans are better than computers at some things: creativity, language, pattern recognition, art, design, reasoning. Computers are better than humans at some things: calculations, memorization, repetitive motion, fast sensors. People seem to think that the future is about making robots that look and work like us, but there's no point. We have plenty of humans. We will build robots that do the things we're not good at. And that means there's no particular reason to use a humanoid form. The future of robots is not humanoid. I think humans with machine parts will become commonplace, but they won't be robots replacing or competing with us; they'll be enhancing us.
In general though I'm quite optimistic about the future. I just think the things that actually succeed won't be the commonplace predictions you see in movies and TV.