While they were wrong about the pen detail (and that wasn't their prediction, PDA manufacturers had pushed the idea of stylus based input for some time beforeha

While they were wrong about the pen detail (and that wasn't their prediction, PDA manufacturers had pushed the idea of stylus based input for some time beforehand) but they certainly weren't wrong about tablet form factor in general which was a large part of pen computing¹ (and contrary to popular belief Apple were from the first proponents of). ---- [1] The hardware wasn't ready though: there were units akin to more recent tables and hybrids (360⁰ hinged laptops or those with detachable keyboards) but at the time it wasn't possible to make them light enough with enough battery life, nor powerful enough² without noisy active cooling, large touch screens that worked well enough without a stylus were too expensive so the pen had to be a thing, etc. [2] At least to support desktop/laptop workloads. People hadn't got used to the middle-ground of powerful-enough-for-what-you-might-actually-find-a-tablet-convenient-for (PDA like tasks, web browsing, video playback, light games, maybe light office work) via smartphones and nobody wanted to try sell a 9+ inch PDA.