This is a pointless knit pick. But, I'm going to pick it anyway.
There is a camp which keeps referring to the 16x9 aspect ratio as wide-screen. While is it certainly wider than 4x3, it is a far cry from actual wide-screen.
First, lets normalize our units, and get the denominator to 1. 16x9 is 1.77 to 1, and 4x3 is 1.33 to 1. The historic aspect ratio is 1.33 to 1, and is found on 35mm film (a film gage dating back to the late 1800's), where the image is 4 perf holes tall, with the line between the frames being the width of the gap between the perfs. Why 1.33 to 1? Why not?
So what other aspect ratios are there? When in dout, ask the google... a href="http://www.film-center.com/formats.html">http://www.film-center.com/formats.html. There are some odd ones, like omnimax, which is oval and projected on a dome, and several 360 degree formats. I guess that would make their aspect ratio infinity to 1.
Most modern movies are shot in Cinemascope. It came out in the 1950's, and its 2.35 to 1. Ultra-panavision is 2.7 to 1. Imax is 1.43 to 1. (HDTV is actually wider than something!) However, be honest, HDTV is no Imax.
So, my final point: a wide screen movie is 2.35 to 1, or at the most generous at least 2.0 to 1. 16x9 is 1.77 to 1. 16x9 is missing 1/3 of the image. It may be wider than 1.33 to 1, but we're talking wide-screen not "wider than TV".
Now lets ponder resolution...
They call 3840x2160 "4K". I call it 3.8K, because I can count. Yes I realize that they just make a 2x2 matrix of HDTV, but I don't care. Modern file formats typically use arbitrary integers for the dimension fields.
4K is 4096x3052, and thats what it has been for some time. Its a real cinema resolution, thats what you get digitize 35mm film. Note that its 4x3. Because thats what the anamorphic image on the film is.
So you have a choice... 16x9 misses 1/3 of the image on the sides. 3.8K misses 1/3 of the image on the top/bottom.
I want a format meeting or exceeding the contrast ratio of film (ten times that of video), meeting or exceeding the resolution of film (where film is defined as Imax), and no compression artifacts (and that includes tricks like 4:2:2 color models). How about some wonderful "digital" system that actually improves quality instead of simply lower cost and more convenience. I want better not cheaper. In the end, the cost of doing a thing to film is pretty much universally greater than the cost of the film.