I've had stills shot with my Contax G2 in 24 x 36 mm film format (nearly the same as VistaVision) scanned on an Imacon scanner, producing a file that's roughly 5155 x 7732 pixels, or 39.9 MegaPixels!
There are details in the image that are about two pixels wide. I'll post a sample here if you guys don't believe me (someone PM me and tell me how to post images properly here).
According to ARRI's "4K+ Systems: Theory Basics for Motion Picture Imaging", audience members with good (20/20) vision can see 4K resolution viewing a 25 meter [82 ft] wide screen at up to 20 meters [65 ft] distance.
I can DEFINITELY hear the difference between 16 bit 44.1 kHz audio and 24 bit 96 kHz audio (and I'm 40 and can't hear above 16 kHz). And remember how Sony told everyone that 44.1 kHz was "perfect sound forever"? [and 1080i compressed HD was perfect, blah blah]
I've heard that some audio manufacturer did a test with sampling rates, and people with good hearing could hear differences until about 500 KHz, then they could hear no improvement above that.
So 96 kHz audio does not surpass the human hear, and 4K digital cinema projection does not surpass the human eye.
5K capture and 4K projection. As Ridley Scott would say "It's a great start".