I don't think anyone didn't think it was possible. Back in '99 I was working on a tablet w/built in phone, and Ericsson had their ScreenPhone around the same time. Both where "tethered" to a base station at home (ours used a custom extension to DECT), I believe, but the intent was always to add proper mobile support.

In fact, when I was first sold on the concept, the guy who started the company talked me through how he imagined a "home base station" that he'd use while there, and how he wanted the device to smoothly hand off to the mobile network if he took it out of the house.

The choice of a tablet over a smaller phone was about a convenient screen size, coupled with the initial devices being tied to the home anyway. But "everyone" around us had PalmPilots, and "everyone" expected PDAs and phones to merge eventually (and they did, sort of, but to see Palm giving in and going with a keyboard was a disappointment).

The challenge was that around the time the iPhone launched, people did not believe the market was there yet, nor that the hardware was ready, largely because "everyone else" had a go too early, failed, and essentially shelved the idea for the next decade as something that was way too early.

What Apple got exactly right and everyone else messed up was the timing.

E.g. we were shopping around our tablet prototype in '99 and 2000 based on a 100MHz or thereabouts 486 clone w/32MB RAM running Opera and a custom UI w/resistive touch. It was a fantastic device at the time, but the combination of not yet being able to provide a proper GSM enabled device, too short battery life, low RAM, slow, horrible resistive touch, and it was a device that would have appealed mostly to a small niche of geeks, but to work financally it needed to be a mass market device.

With the available hardware in 2006 we'd have a great starting point if we had started around then. But when we started in '99 the discussion was never "can these hardware constraints work in a way that can appeal to a mass market?" but "this is the price we need for it to work as a mass market device, and here are the tech specs that can fit within that price" and then we tried to make something that could be mass market from that... way too early.

To be clear: I'm not trying to downplay what Apple did. They made a product that appealed to a vastly larger market because they understood. But it wasn't because nobody else believed in touch enabled smart phones or tablets, but because they approached it from a usability and marketability perspective first, while everyone else were thinking like geeks willing to sacrifice usability for a "imagine if.." ideal of devices that were ultimately quite unfulfilling.

When the iPhone came out, a lot of us were pretty much "so what?" because we still did not understand the significance of that wait. We'd seen full screen touch, and we'd seen PDA's married with touch, and we'd seen larger tablet type devices (basically laptops with pivot screens mostly), and the iPhone to many people who'd been through the first round of hype around these type of devices just seemed like more of the same at first.

Until it became clear just how much of a difference the hardware advances and Apple's design had made to the whole thing.

We absolutely agree about their timing, and I think it's important not to underestimate how important it is to understand when the time is right and not get caught up in constraints that applied last year because that's when you started thinking about it.

It's very possible that we'll see something similar with cars. A lot of people have worked on driverless cars for a very long time, and the question is how much of the current designs are based on preconceptions that seemed to make sense a few years back, but where things can be done better today.