Okay... Reality check... The smallest pixel to date is 0.03175 of a mm, but it's scarce...
All big companies usually gobble up all the supplies.. This is 800PPI so theoretically you are right... Cost? Well name a price... They are coming and yes! They would have to be for VR or the pixels would be too small for normal TFT display's
IPhone 6 has 326 PPI at 0.077mm which will be 652 pixels in 2".. But as yet no one makes smaller units.. Phones normally start at 3.5" But still not in your requirements...
I hate being pessimistic, as someone has to get the ball rolling..