Just a technicality, but a 1080p display can be considered 'retina' if the display is small enough or typically viewed from a far distance. The display on the iPhone 6 Plus is 1080p. It qualifies as a 'Retina display' because of its high pixel density and the typical viewing distance of 1 foot.

Retina is, at best, a standard of pixel density, in general it's just marketing.

Standard on phones yes, but the PC market has not yet caught up. A 1920x1080px monitor is still the baseline.

GP was referring to Desktop screens, not laptops, I believe. Those are AC powered.

Indeed. The thing I find surprising about laptops that one has basically choice between a HiDPI screen, or a 1366x768 "Everything is blurry" screens.