> Both handhelds and desktops have been increasing in resolution, and decreasing in cost, for years.

That's not entirely correct. 24" at 1920x1200 and 30" at 2560x1600 is something that's been there for years, and these days laptops are regressing rather than progressing: in 2005 I had colleagues with 15" laptops in 1920x1200, these days the majority seems to be 16/9 screens in stupid resolutions (1366x768 seems really common these days in entry-level laptops)

> Never is a mighty long time!

My never stands for the Macbooks, and probably the iPad as well. By the time we reach the ability to create such densities with acceptable yields on panes bigger than 10 inches, the current names will long have been retired.

You wouldn't need anything like 4000x3000 for 'retinal indifference' using the article's number of 287ppi@12" use distance as a basis for that threshold. 4000x3000 pixels, assuming a 22" screen is about 227ppi. The threshold in the article, translated to a typical working distance for a laptop of 22" is about 156ppi. So a 22" diagonal screen (same aspect ratio as your 4kx3k) would only need 1850 pixels on the short side to hit the 'retinal indifference' number.

Oh, and some other smartphones crossed into retinal indifference at their typical use distance sometime late last year.