So why not have all forms of computing?

Horace Dediu, on why each new computing interface tends to add to the others rather than replace them:

The touch UI did not immediately obviate the need for traditional personal computing interfaces. The smartphone brought computing to more people and more contexts but keyboard and pointer computing cannot be fully replaced by touch. We have a situation where there is co-existence between touch and non-touch computing. Indeed we also have sensor computing in the form of Apple Watch and AirPods. Perhaps there were will also be Apple spectacles to expand the compute real estate on the body.

Intent computing will probably reside primarily with our phones and wearables but Spatial Computing will strengthen their position alongside keyboard computing. Spatial was always a “high commitment” interface. To use it you strapped in, settled down and became acclimated. Then you became productive. A session was going to last at least 20 minutes, perhaps even a few hours.

Intent computing is a few seconds of use. Perhaps a few seconds strung out in multiple sessions but it was far more “glance” computing than “sit down” computing.

So why not have all forms of computing?

As the diagram on the coral of life shows, evolution results in a multitude of “form factors”. Some do become extinct (see the scroll wheel iPod or the stylus PDA.) But most survive and coexist.

I agree with Horace. Intent computing will build on top of the platforms we already have, not replace them. An AI pin isn't going to displace the smartphone. Even when you can just ask your phone to do something, you'll still pick it up to read, watch, and look things up.