REASONS WHILE TABLET COMPUTERS WILL BE A BUST:
1. First, to define the bust: just because they sell a lot of them for a couple years, and you see a lot of jerks carrying them on the plane or in the coffee shop, does not mean they are a success. I predict this will be a fad. Everyone will talk about tablets for a couple years, maybe even buy a bunch of them, and then everyone will be on to the next niche gizmo.
2. The main reason: screen vs. keyboard. The Internet has been drifting away from Flash, which means that although there are some pretty nifty graphical interfaces out there on the Net, the content is largely text-based. Having large screen real estate helps with text, but the fact is, the Internet is 50% contribution, as much as it is consumption. Typing is the main interface between brain and Internet. Voice is good enough for phrases, but try saying "backspace, backspace, backspace, highlight, delete, cut and paste", and then do it with a few key strokes. You have ten fingers, but can only say one word at a time. Brain scanning is not there yet. And gestures... well, until I see a multi-touch screen that responds as fast as a physical button, a keyboard is simply going to win. Even mouse and keyboard together is faster and easier than touch screen and keyboard (there's been a touch screen in the center of your laptop for about ten years now).The hunt-and-peck folks might be able to get by with a screen-keyboard, but anyone who types regularly over 60 wpm is going to need keys and physical buttons. Slowing down the data entry interface to make a slick device is like taking off the steering wheel of the car to make the dashboard smoother. Sure, you could pilot your auto with a fly-by-wire joystick. But who would want to? Same goes for screen data-entry. Just wait until you need to CTRL-ALT-DEL your touchscreen.
3. It's not a cell phone. I LOVE my iPhone. Why? Because it let's me use my phone and mp3 player in such a way that it takes over a lot of my use for a computer. It fits in my pocket, it is light, fast, and convenient, and it allows me to do things I couldn't do with any other device. A tablet computer is none of these things. It is too big for the pocket, too slow for real typing, and unless the screen is as big as my laptop, it's a strange web-browsing, media-watching niche between small and big enough. You don't want a cell phone the size of your laptop, and you don't want a laptop as small as your cell phone. And,
4. There are already netbooks, and they are on their way out. This is the sort of fad I see tablets becoming. Just like it was cool to have a mini-laptop, it will also be cool to have a giant iPhone. For a while. If battery time is good, it could be a way for people to have a cheap, more portable computer. But still, it is an awkward size. Given the choice, you will either carry your smart phone, or use your real computer. The main effect of notebooks has already taken place, and this is:
5. Gadget evolution. Notice how there are no mice the size of bears, and no bears the size of mice? How about how there are no mice of various sizes, and no spectrum of bears. Evolution causes entities to find a particular niche, and become specialized for that niche. There is no need, and no likelihood of survivability, for a species to exist in various sizes. The species will either evolve large or small, and then tend to stay that way. Same thing goes for technology. Netbooks had their effect. We realized maybe our laptops were too big and too expensive. But very few people carry around a 7" Asus anymore. 10"-14" produced the greatest survivability, and so netbooks got bigger and more expensive, laptops got cheaper and smaller, until we got to a certain equilibrium. Same thing with cellphones. The screen got bigger, touch screens multiplied, features became standardized. But in the evolutionary genus of Internet-capable devices, this speciation has already occurred. Tablets are going to be a post-facto dinosaur. The are going to arrive on a scene filled with competitors, and not bring anything new enough to survive.
6. But what is new about a tablet? What niche could it fill? Basically, it adds a giant touch screen. What could this be good for? Games, media playback, maybe other highly-visual apps like AR schmaltz, or synced environment control. eBooks, maybe? All of these seem pretty specious at best. It could compete with the PSP and Nintendo DS, perhaps--devices with input interfaces specific to their use. This is what the tablet will be--a bright, shiny, relatively expensive (for its niche) device that engenders applications specific to touch screens. The iPhone app store was a huge success not because of the touchscreen, remember--it's true innovation was portability and mobility: putting applications in your pocket and in the palm of your hand. Now that this has been accomplished, what apps will be tailor made for your fingers, and your lap? I could make a sexual joke here, but perhaps you already see my meaning. This device is bringing innovation to a place where it doesn't have any room to expand. I see a lot of board game apps in the tablet's future.
Now, I could be totally wrong, and maybe there is some amazing application out there none of us have foreseen. Maybe this will replace barcode scanners, Symbols, and other larger handheld devices. But still, we are looking at a marginal niche at best. Until someone re-invents the keyboard--not just overlaying it onto a touch-screen--the keyboard is going to be the main interface for the Internet. Nothing else can keep pace.