[tesseractive]

There have been high-end Windows laptops for a while now that had higher resolutions than Apple was willing to go. For example, for several years, Sony has had a 1080p option on the Vaio Z's 13" screen. That's a lower PPI than the Retina screen, but it's a much higher resolution than the 1366 x 768 resolution of a MacBook Air.

Nowadays, I think 1080p screens are starting to creep into even smaller 10"-11" devices. And with the light Apple is shining on high resolution screens now, I expect this will accelerate, and we'll see more high resolution screens on laptops filtering down from specialty PC laptops to midrange ones, and extreme high resolution screens start to show up on the specialty ones.

This is a lot like how it worked in the iPhone vs. Android world of phone resolution. Android phones jumped up to 800x480, then the iPhone jumped all the way to 960x640. Android stayed at 800x480 at first, then 960x540 (qHD) screens became more common, and now a device doesn't count as a high end Android phone unless it has a 720p screen, a higher resolution than the iPhone (though usually at slightly fewer PPI because of the different screen size).

[seanmcdirmid]

You can't just upscale most apps for a higher PPI. The art is mostly pixel based and upscaling will create artifacts. So for some boosts in resolution, this is ok, the art just gets smaller, and app developers slowly adapt by making their art bigger. But from 1X to 2X...upscaling works a bit better but is still not ideal, while you really have to go and completely redo your pixel art.