Mmm, people have been getting great images for decades without seeing the moment the image was taken. A lot of lucky people.
There will always be a delay from seeing the moment to pressing the shutter to capturing the image. Unless Sony have timed the Shutter press to capture the previous few milliseconds of the video that was passing through the camera delayed for the time of the average person takes to react to the scene, which could be possible, just because you see it, doesn't mean you have got that moment, even with 20 fps.
My first digital camera in 2003, a Fuji S602Z Pro, in a burst mode would continuously take images until you released the shutter button, and then save the previous number of images. Will the A9 technology improve the capture rate for the 'moment'? Time will tell.
24Mp may be the 'sweet spot', and with the D850 you can have 25Mp in the medium setting, and RAW too for those that want it.
From what I have seen of the Eye AF it looks very good, but again, people have been focusing and getting excellent images for decades with primitive AF, and the AF on the D850 is far from primitive.
Improvements in AF should always be applauded and welcomed when they work, but if it is not possible in a camera you want then you learn to work with what you have, or will get when you buy.
Maybe a follow up to the Sony A7RII will have the improvements of the A9 and the resolution options of the D850. But for some it won't matter, because it will have an EVF.