Not going to happen, imho.
First it's technology as mentioned above.
Second there is the resolution itself. With iPhone's retina display you still have less pixels than the iPad's display so no problem renderinf apps. But on notebook everything would be so small. Of course, OS X is not resolution independent, but imagine even HD video looking ugly on such a display because of interpolation.
BTW I can't see pixels on my HiRes MBP from normal using distance anyway, so no problem.
And, BTW again, I work with graphics, and for example when drawing letters in FontLab, the pixels of the display are not precise, but you can never work only with any display's image as there is always the need for a relatively fine laser print. And all the graphic software (Illustrator, FontLab etc.) has limited percentage of zoom. So with this 1680 by 1050 display (slightly above 120 ppi I believe) the image even zoomed at maximum is sometimes nearly too small.