The newest 6gen NUCs come with HDMI 1.4b and it was a corporate decision.
Resolutions are below:
The port is compatible with all ATSC and DVB HDTV standards and supports eight full range channels at 24-bit/96 kHz audio of lossless audio formats.
The maximum supported resolution is 3840 x 2160 @ 30 Hz and 2560 x 1600 @ 60 Hz, 24 bpp (WUXGA)
Mini DisplayPort compliant with DisplayPort 1.2 specification.
The maximum supported resolution is 3840 x 2160 @ 60 Hz, 30bpp.
Every newer NUC generation improves the features of the previous versions. Hopefully the next NUC gen will introduce HDMI2.0. The date of release is going to be available in the main website of Mini PC: Intel® NUC
If you really NEED the full HDMI 2.0 3840x2160 @60Hz, there are a few ACTIVE adapters that will convert DP 1.2 to true HDMI 2.0. There are also a number of passive adapters that say they support DP to HDMI 2.0, but don't actually output 60Hz. Be sure the one you buy specifically says it will do miniDP 1.2 to HDMI 2.0 3840x2160 @60Hz.
I have not tested, but this one is worth a shot:
That really depends on the user, and the content you are watching. Almost no video is actually recorded in that format. 1366x768 @30Hz is plenty for most. 1920x1080 @30Hz is enough for just about everything. I see no need for anything above 60Hz at 1920x1080 with the majority of what is currently available.
Blu-ray is only 1080p (1920x1080) @ up to 60Hz. For refrence, DVD was only 720x480.
4K Blu-ray is just now hitting the market, although no one is buying. It is capable of 3840x2160 @60Hz, but almost all 4K content is still only encoded at 24fps.
Anyone complaining about the 6 series NUC's not natively handling HDMI 2.0 is just a spec-wh0re. If their concern was fps for gaming, they would not have bought a NUC!