I think there is a class of device here that is missing. Low power but forever devices that have some basic functionality. Over time I could see this taking over laptops and the like as ultra-low-power became more and more capable.
On that note, whatever happened to netbooks? As someone who writes a lot and need a mobile device to do it on, they used to be perfect. Can't seem to find the form factor anymore. Even the smallest Chromebook seems only slightly smaller than a laptop.
Windows Vista and Windows 7 happened to them, and Android/iOS tablets happened to their target demographics.
And notebooks got much lighter and smaller on average, compared to the netbook era. You used to need a 14" or 15" notebook with an inch worth of screen bezel to get a "full-powered" CPU and enough RAM to have a reasonable desktop experience, plus an unwieldy docking station to have enough ports to wire it up to a work place; netbooks were tempting companions to that.
Today you can get a full desktop experience (and even some fairly high end graphics capabilities) with a 13" laptop that's smaller than 11" subnotebooks and ligher than most netbooks used to be, and can fit a full keyboard.
E.g., a modern Asus PX13 is about the size of an 11" Asus eeePC, and just as heavy… but it comes with a 24-core Ryzen CPU, 32 GiB RAM, and an RTX 4070. If I'm on the move, I can just take that, instead of buying a companion device, and if I'm in the office, I can connect it to multiple daisy-chained monitors with connected peripherals using a single USB-C cable. Other Windows vendors have similar offerings.
And that's just looking at direct equivalents; completely ignoring the Apple-sized ARM elephant in the room. The M series CPUs are nuts in terms of performance, but the battery life is comparable to netbooks.
> Even the smallest Chromebook seems only slightly smaller than a laptop.
For a while companies made ChromeOS tablets to fill the gap between notebooks and Android tablets, but the higher end Android tablets these days have cannibalized that market too. And "higher end" is relative; netbook prices (400-ish dollars) get you fairly capable 10"-ish tablets from multiple vendors, complete with precision stylus and keyboard/touchpad cover. That's big enough to get netbook-tier keyboards (which were never great, let's be honest), but small enough to fit in cargo pants pockets (very handy for air travel), and the battery life is measured in days.