[rorrr]

These screens are insanely expensive, and wouldn't make much sense. Nobody is looking at 27" monitors from such a small distance to distinguish between retina and simply good resolution.

Plus, I don't think there are affordable video cards to drive resolutions like 5120x2880.

[ScottBurson]

Well, you make a good point. For comparison, my 17" MBP is at 133 ppi (1920x1200), while the base 15" is 110 ppi, and so the Retina 15" is 220 ppi. If you wanted the 17" screen to be around 220 ppi, you could go with 3072x1920, which would noticeably easier to make and to drive than 3840x2400. Given that full-size screens are usually viewed from farther away than laptop screens, I think it's fair to offer this as a "Retina" resolution for a 24" 8:5 screen.

Similarly, the 27" 16:9 screen could come in at maybe 3584x2016.