I admit that I'm biased toward personal interests and hobbies but my first thought was an Oculus Rift that fits more like a pair of shades than a pair of ski goggles.

And of course the ever-present dream of "smart" contact lenses that can adjust how incoming light is magnified on an adaptive basis or offer AR functionality without any headgear at all.

Obviously that sort of application is years away regardless of how this particular project works out. Still, this stuff does lead to some fun brainstorms and geeky fantasies.

Optical discs are generally using the smallest light they can manage, can colors even help?

Plus they're focusing on a single point, so I don't think chromatic aberration would be much of a problem in the first place.

If they can play fancy tricks to get a smaller focal point relative to wavelength, that would be a powerful improvement. But still probably monochrome discs.

This reminds me of an explanation I read a long time ago for why FM radio is so much clearer than AM. This doesn't really approach your question of informational density, but I thought it was interesting.

If you're driving down the road and someone is shining two lights through the trees. One is white light and merely changes brightness, while the other rotates through three colors. Which light is easier for you to detect changing?

It could be something akin to holography.

To put it simply, they can have the same optical density, but re-write over it several times in other colors. The same lens can observe and read the exact point, interpreting the data in (for example) blue, green, and red.

That is something that's possible, but I doubt its practicality. The longer wavelengths can't store as much data even under ideal conditions, and squeezing them in causes interference that hurts the density you have on the best wavelength.

Plus you would need a much more elaborate disc-pressing mechanism.

Much simpler to add more monochrome layers.