The personal computer and the smartphone are amazing, and will almost certainly remain pillars of computing for the majority of our lifetimes. Beyond those two major portability and productivity classes, you hit diminishing returns.
Portability is critical to modern device usefulness, and there are only two classes that matter anymore: always with you, and not.1 Devices that are always with you must fit comfortably into pants pockets without looking stupid. If you’re exceeding the size of pockets or small handbags, you’ll need a bag of some sort, which means you can carry pretty much anything up to a full-featured modern laptop. (Ultralight laptops are extremely capable these days.)
Smartphones dominate always with you. There are situations where people won’t carry one — besides the obvious ones like sleeping and showering, the most common one I hear is jogging — but these are few and far between, and will shrink over time as smartphones get smaller, cheaper, and more durable.
Tablets sit in an awkward portability class: they aren’t that much more useful than smartphones, but aren’t much more portable than small laptops. I think they’re still (barely) justifiable as a mass-market category because they’re not much of a burden to make and support because they’re just smartphones with larger screens — they have roughly the same hardware, software, and applications, and are better than smartphones at tasks that benefit from more screen area.
But why do we need “smart” watches or face-mounted computers like Google Glass? They have radically different hardware and software needs than smartphones, yet they don’t offer much more utility. They’re also always with you, but not significantly more than smartphones. They come with major costs in fashion and creepiness. They’re yet more devices that need to be bought, learned, maintained, and charged every night. Most fatally, nearly everything they do that has mass appeal and real-world utility can be done by a smartphone well enough or better. And if we’ve learned anything in the consumer-tech business, it’s that “good enough” usually wins.
This is why I’m down on new-hardware-category fetishism and why I’d rather Apple not overextend themselves further for a watch. We already have extremely powerful devices that we’re barely using the potential of — we don’t need to divide our attention and resources further to add new device categories to our lives that aren’t massively better in normal use than what we already have.
PCs made many other devices redundant or obsolete in the ’80s and ’90s, the web demolished many legacy businesses in the ’90s and ’00s, and smartphones have obliterated many more old products and businesses in the ’00s and ’10s.
The combination of a computer, internet connectivity, and a smartphone (and maybe a tablet) is awesome. It satisfies nearly every modern demand for personal computing hardware and still has massive untapped potential for software and services.
Maybe that’s all we really need for a while.
Cameras have a similar dynamic: smartphones became everyone’s always with you camera, SLRs and SLR-like models dominate the high end, and point-and-shoots are obsolete and redundant.
But cameras have it even harder: smartphones have compelling photo features that cameras will never get such as social apps, and the high end will likely shrink as many hobbyists and prosumers abandon their SLRs and go smartphone-only. ↩