The question I have is, wouldn't this reduce the saturation, and thus resulting in a display that wouldn't cover the entire 2020 gamut? My understanding was that on the CIE chart, the curved top line represents single wavelength colors, see here, with labels for the wavelengths:
"The curved edge of the gamut is called the spectral locus
and corresponds to monochromatic light (each point representing a pure hue of a single wavelength), with wavelengths listed in nanometers. The straight edge on the lower part of the gamut is called the line of purples
. These colors, although they are on the border of the gamut, have no counterpart in monochromatic light. Less saturated colors appear in the interior of the figure with white at the center."
So if you start adding more wavelengths to the colors, it will start desaturating them and thus "pulling" the primary position in towards the center, resulting in less than full coverage. Of course this leads to two questions:
1) Given the "straightness" of the curve at the R, G, B points, would a bit of "spreading" of bandwidth there significantly affect saturation/coverage
2) Would a little bit of bandwidth spreading even have a substantial effect on solving the color perception problem JK talks about.
It would be interesting to see an article about the monochromatic color issue JK talks about.
On a related topic - I hesitate to suggest this, as it is likely to generate a flood of - you can't do that responses. Most LCD TVs and projectors have built in color primaries that are wider than rec 709. Then to achieve rec 709, a mix of these primaries (via LUT or 3x3 matrix mult) is used. Now these primaries are not as wide as DCI-P3, but they wider than rec 709.
Oh, it's definitely possible, this is how color management on PCs works. When you profile your PC monitor, it doesn't (necessarily) pull the primaries into specific points, it creates a map of the displays capabilities, so that when you have a source with a known colorspace (ie a picture on a website that is sRGB), it can be accurately mapped into your displays capabilities.
Here's a short discussion from Adobe: