A big tablet imply (imo) to be standing and looking down (even if you sit you have to look down). This posture will get tiring very fast. Most people can stand all day but their necks won't forgive them this unnatural position.

Also the author seems to forget that "The Forgotten Man" usually write a lot of stuff (reports, emails, code etc) and a stylus doesn't solve anything here.

Even with perfect OCR you'll type faster on a keyboard than writing with a stylus.

So yes, big tablets are probably coming but "The Forgotten Man on The Forgotten Desktop" will still be a thing.