One thing that I'm not sure is generally understood is that Samsung etc. are advancing folding-screen phones, and MS is jumping back into phones with a dual-scr

One thing that I'm not sure is generally understood is that Samsung etc. are advancing folding-screen phones, and MS is jumping back into phones with a dual-screen model, for just the same reason that Apple is apparently working hard on AR—and the reason isn't simply to have something new to sell smartphone users. It's because the usability of the smartphone as an all-round personal computing device is now massively bottlenecked by its small screen, and if you simply make that screen bigger then as soon as you go beyond phablet size you simply end up with a tablet, too bulky to carry all the time in your trousers pocket. And when the alternative is an overly-small screen too close to the eyes then (present and near-future) AR/VR drawbacks like low pixel density are not so bad in comparison. (One snag here is the bulk of the AR HMD itself: we'll have to see what Apple has done on that front.) Laptops have that problem to a lesser extent, being unequivocally on one side of the screen-too-small/device-not-ultraportable tradeoff, but AR/VR is going to displace (or at least supplement) the laptop clamshell screen too, and it will eventually come for desktop monitors as well.