Personally I would love to see displays made grids of hexagonal pixels, and maybe 7 primaries. Since almost every image that goes to displays today already needs to be rescaled at runtime, the processing shouldn’t need to be impossibly much more expensive than current square-grid resampling.
I would also love to see digital camera sensors with more primaries in a better pixel arrangement.
But the primaries can be relatively close together in color. It’s fine if we have e.g. 2 reds, 2 blues, and 3 greens instead of 1 of each.
Or for an LCD, some of them could be broader-spectrum primaries which were brighter but less colorful, while others could be more intense narrow-spectrum primaries. This would make the display more color accurate for various observers (more robust against “observer metamerism”), and would make the display overall brighter for the same intensity of backlight.
Or I dunno.. I’m not an expert in display technology, I’m sure the engineers could come up with many ideas.