Yes, point - not line! - resolution is ultimately noise limited, not optically limited. Until you get to astro-size fixed installations, that is...
Canon's effective pixel area has never been 100%. In the 5D classic, I think we measured 47%, with the newest "100% coverage microlenses" I'd guess they reach maybe 80%. The collimated angle light efficiency depends on how strong you make the micro-lens, and how far above the sensor surface proper it is situated. The actual light-sensitive area on the sensor is smaller than 50% in most CMOS cameras (excepting back-lit of course...). The microlens has to be absolutely centered above this area, with an angle compensation for an estimated average main lens exit pupil distance (usually around 70-80mm) in the corners.
As soon as the ray angles stray outside of the optimal, the microlens starts to both reflect (due to a very high incident light angle) on the far side of the dome, and project outside the sensor active surface on the near side of the dome. In Canon sensors, this is usually at about F2.4. From F1.6 down to F1.2 region of angles, less than half of the original light amount reaches the active pixel surface. There's a built-in compensation for this in firmware, that you can trace by looking at the gaps in the raw file caused by integer multiplications...
BTW, the MaxMax microscopy images show a line spread of about 0.4 pixels, not one full pixel... The full spread is about 0.8-0.9px, giving a +/-0,3px line spread after subtracting birefringency loss (the ghost image is almost 2Ev down from the non-refracted image). That is usually enough to give the interpolation engine some neighboring-area support to work with. This small increase in support can increase the interpolation accuracy by several hundred percent.