I had a 4K camera, none of my clients cared about 4K, none wanted 4K footage. Sold the 4K camera, bought a 1080 camera (Canon EOS C100), it's been great. Do work for Fox, Sony and a few of the other studios. That said, beginning some new projects for Netflix and Amazon and they REQUIRE 4K origination and masters. So it depends on the client. I mainly shoot docs and EPK and few require 4K, yet, but they will eventually. When they do, will weigh buying an FS-7 or C300 MKII versus just renting. If they book enough days, makes sense to purchase, it it's just a day here and there, rental all of the way.
I'm currently HD and HD, but I bough the URSA Mini 4K back in January because of the obvious advantages over the T2i that I previously used, plus it's a camera I can grow with. 4K isn't mainstream yet, but when it is, I'll be ready without needing another camera.
For what I work on almost all Arri work is 3.2k ProRess 4444 in LOG capture and ProResHQ 1080 deliver. When using Red it's almost always 5k-6k capture and 1080 finish with maybe a 4k master that sits on a hard drive for 'the future' lol.
IMO the 3.2k is a good place to be on Arri. I think 6k on Red for 1080 delivery is overkill and often results in so much data. But hey, it's not my harddrives.
I notice that none of the DCI projection formats are incuded. Obviously not relevant to the bulk of general commercial/industrial video work. But what about special event presentations, festival films, theatrical, etc? Anybody shooting 2k/4k scope for corporate events? I used to do such events in scope format with 3 stack 35mm slide projector setups.
I'm mostly shooting 2k DCI widescreen projector format 2048x1080 for personal creative films.
HD:
VariCam: P2 mostly 720/60(59.94)P and 720/24(23.98)P. Maybe 1% 1080/60(59.94i)
C300: MXF mostly 1080/24(23.98)P, some 720/24(23.98), slo-mo 720/60(59.94). Have done 1080/30(29.97) and 1080/60(59.94), but those are RARE exceptions.
F55: XAVC 1080/24(23.98)P; ProRes 1080/60(59.94i)
Most of my clients ( nearly all ) are still in HD. But lately some have been wanting 4k so that they can "cheat" the single-camera as two cameras. Their final product will be HD but shooting 4K allows them to cut the single-camera between wide and tight without resolution issues.
The unfortunate part of that is it takes away creativity from the DP / Cam Op. The clients only want a boring wide lock down shot. Post production, and not the DP, chooses when to go in tight and when to come back out wide. No more floaty closeups performed by the camera op. No more closeups that drift from the subjects hands up to their face.
Of the 300 or so days my Fs7 has worked since purchased, maybe 10 of those have been 4K. But better to have 4k able camera than not have 4k able camera. Especially considering the price differential is negligible. If you don't have a 4K able camera and you miss a 5-day job because of that, the income you lost was as much as a 4K-able camera would have cost over the less expensive camera. Even if you have a steady client who only shoots in HD, you are screwed as soon as some higher-up decides they need to be shooting in 4k. But I suppose that is something one could wait to deal with only when they have to deal with it. Me, I'd rather be ahead of that curve. Even if it meant I had to purchase a used 4K capable camera instead of a new 2K camera.