Ron Jones posted on the 4K Blu-ray UHD thread:
"Remember that HDMI allows the source and the display to negotiate to agree on the best format supported by both devices. We know that the current Sony 4K displays are limited to 4:2:0 with 8-bits at 60 Hz but what formats can they support at 24Hz, which is what we will be dealing with for most future movie releases on 4K Blu-ray? 4K video @ 24 Hz using 4:2:2 at 12-bit depth is within the bandwidth limits of HDMI 2.0 chips that can only go up to 10.2 Gbps (which is the case for the latest Sony projectors). So this would not be a HDMI issue and if the Sony projectors cannot support this format then that is strictly a limitation in the projector's internal processing. I looked at the operating manual for the VW600ES and found tables under the heading of "preset signals" on pages 53 and 54 and found that for the 4096 x 2160 and the 3840 x 2160 signals that are at 50Hz and 60Hz there is a note that says "Available for YUV420 format signal only" which means 4:2:0 format. However for those 4K signals at 24Hz and 30Hz that note does not apply. The omission is they don't actually list what other chroma subsampling formats and bit depths they actually do support for input signals at the lower refresh rates. So perhaps 4:2:2 is supported at 12-bit depth is already supported after all. Do you have any info from Sony as to what the actual supported formats are for 4K @ 24Hz signals?."
Though I disagree with Sony's decision to go with the 10.2 gbps chips, doesn't Ron's post that 4k Blu-ray movies will run at 24hz and even the 2.0 hdmi standard with 10.2 chip will allow for 4:2:2 at 12 bit depth show that our concerns may be for naught? How many 4k discs will ever be mastered at 48hz, like the Hobbit...hardly any.