David wrote:Post-capture sharpening makes diffraction blur WORSE, so it’s not much of a solution.
This seems to disagree with
the video embedded in the petapixel article?
Also, you're talking about there being an "aperture limit" when diffraction becomes noticeable, but - as the video points out - diffraction is effected by the lens; a higher resolution sensor makes diffraction more visible at wider apertures because it can resolve greater detail - it does not increase the distortion, and thus cannot result in lower quality in the overall image.
If the DLA for this new camera is in the ballpark of f/4, from f/8 onwards you are going to struggle to get clean images
If you want "clean" images, leave them to soak overnight in white spirit.

The biggest concern for more megapixels should be the processing/etc concerns you leave to your penultimate paragraph.
With the rate camera technology is advancing, it makes me wonder if anyone will create a specialised photography-specific processing unit. Sure, Adobe is (attempting to) use the power of graphics cards to run their algorithms, but having camera manufacturers implement them directly in dedicated hardware allows even better performance that might be necessary if/when this number of pixels becomes more common.