In addition there�s the quantum noise being only dependent on temperature. Without cooling you can�t reduce the noise much more. To some degree it may be removed using software, but then that�s another type of interpolation...The very fundamental limits (wavelengths of light, diffraction limitations, etc.) won't be changing as pixels get smaller and noise gets lower.
I doubt if we see any significant increase in pixel count on APS size sensors. Maybe up to 9MPix, but not more. Maybe a 9MPix APS size Foveon sensor is all we can hope for.
DagT
