3-d printing since it will make design and manufacture of tons of good decentralized and far cheaper for most people.
Prognostication is fun!
Computers -> Internet -> cell phones is a bit of a false lineage, since you’re really looking at two technology strands (communications and computing) that aligned in an explosive way.
Smartphones today are simply pocket computers with always-on Internet access. That tech will be refined, but there’s only two ways it could be supplanted: wearable computers or physically-embedded computers. The latter is, I think, inevitable, but years down the line. The former will, I think, be forever niche. I think smartphones have found a perfect level of integration already; they’re easy to transport, don’t require you to wear anything silly, and can ultimately be turned off if you want to escape. I think they’re in a sweet spot, and I don’t think they’ll change too massively for a while if ever.
Tablet form-factors are a huge deal now, but it’s a glutted market. Every company is fighting over the space because they know that tablets are a niche now but will be standard in five to ten years.
I think the biggest breakthroughs will be in software, specifically in software that helps people feel “at home” in technology. Curation services and increasingly natural and “human” social networking technology will be a huge deal.
My actual guess is that the real “next big thing” will be top-to-bottom, whole-life-management ecosystems. Combinations of scheduling, information, automation, health and finance monitoring, and productivity software combined with time-and-life management methodologies. These technologies exist now, but they’re disjoined, modular, inconsistent, and a bit fringe. I think the major players in the tech space (MS, Apple, and Google) will start building hooks into these systems on a more basic level.
There’s multiple reasons it’s in the companies’ interests: first, it’s a powerful sell to customers if you can meaningfully suggest that your tech will actually improve their moment-to-moment lives. MS has already taken that marketing approach with WP7, but it’s mostly marketing at this point. Most companies are already developing tech in these spaces, and the more they integrate services, the closer to “whole life management” they will be – heck, Google essentially has all the tools up and running, but they don’t all integrate well and they don’t have a central philosophy for how to use their tools. But it’s also a huge way to “lock” users in – once people start considering tools crucial to their moment-to-moment lives, you’ve got a customer for life.
Alternately, 3D printing. 
I love the concept, but I haven’t seen many examples of useful STUFF produced by 3D printers. I think 3D printing will take off first in a “neighborhood shop” fashion – stop by the printer on the way home to pick up a few one-offs. In-home installs seem like a enthusiast thing for a while. A few “killer objects” could change my mind in a hurry, though.
We already have the basics for my choices, but they’re not omnipresent yet, so I think that they’re in the spirit of the o.p.
Bio metrics, we won’t have to carry i.d., driving licences, keys or credit/debit cards.
Once scanned you can unlock your door, drive your car, make a purchase.
Simulators, you won’t play a video game, you’ll be in the video game.
You won’t watch t.v or a movie, you’ll be part of the event with all of the sights, smells, breezes, temperature(modified of course) etc. around you.
Nano technology, I’m not an engineer so I honestly don’t know whats going to happen, but those “in the know”, assure me that its going to revolutionise life as we know it.
Green energy, no I’m not a tree hugger who believes that it can replace conventional sources of power, but I think that it will come into its own supplementing the energy bills of individual premises.
Homes, factories,farms, military establishments, etc. with their own solar panels/wind turbines cutting down of the use of power from the grid.
A bit of wishful thinking for my last choice, but it does have merit, even if I say so myself.
Airships, used for bulk, or high value transportation, direct to its destination without having to be unloaded and then reloaded at seaports or airports
Agreed.
I think one of the biggest changes coming will be in the interfaces themselves. We’ve got primitive speech recognition and touchscreens now. And I suspect that we’ll be able to have near Turing-level conversations with appliances, vehicles, etc. in the near future. Changing your destination on your car’s GPS could be a conversation along the lines of: “No, [pointing to screen] I want to go here, and skip tollbooths on the way.”
I suspect that with ubiquitous RFID use, my kids will someday be able to ask their kitchen/fridge to produce a recipe for tonight’s dinner based on what foodstuffs are currently on hand, and have a verbal interchange with it about what groceries it should order next week.
Excellent
Smellovision.
It’s due.
Just coming in to say 3d-printing
specifically though, the real money isn’t be going to be made from the hardware but by the person that manages to get on top of the design market.
If someone can come out with an iTunes type marketplace for 3d object patterns that have come with actual engineering input (ie coffee mugs that are none toxic and don’t melt, chairs that don’t collapse when people sit on them), at precisely the right time and avoid the temptations towards obscenely greedy pricing, they will make mad crazy money.