Well, this week finally was approved the standard HDMI 2.1, the specification which defines details about how this type of port works. Today’s HDMI commonly seen are the ones which can hold 4K resolutions at 30Hz and at 60Hz, being the last one the 2.0 standard. The new 2.1 defines 4K connections under 120Hz refresh rates. This means that soon the video cards manufactures and monitors aswel will start providing the market with this feature. If you were not yet started developing solutions with 4K in mind, go for it. It will be a must, since the tech will be more and more common at everyone’s home and starting now, will mean the next 1-2 years you will have a good workflow and ready-to-market stuff for selling… hopefully games and I wish everyone selling assets too!
It doesn’t really mean anything. People already use 4k monitors today over displayport.
the new specification enables up to 10K displays, this is not as great as having better 4K, since today’s monitors at 4K only at max 60Hz, not 120Hz. Higher refresh rates means smooth gameplay, but hardware wise, this is a challenge, anyway I dont like 4K at 60Hz. If you compara 1080p at 120 or 144Hz you have to understand that even possible have games at 4k, the experience is not great, thou having a large area for using 3D tools it really helps.
there will exist an even higher demand for 4k titles “soon”
It’s a cable that nothing uses yet, no consoles or GPUs can even drive that. Nothing’s changed. 10k is nothing more than a dream right now, games running at 4k is hard enough and you don’t see consumers buying anything higher than 4k anyway. Ask again in 4-6 years and then maybe it’ll be a concern for game developers, but between the speed it’ll take for hardware manufacturers to actually make new TVs and monitors that high and the speed it’ll take for consumers to get it, I don’t think until then it’ll really be something we need to think about.
To be honest, my 4K TV could use it since the current cables run out of bandwidth when I try to run 4K HDR @ 60 Hz with no chroma sub-sampling 
Unless your TV has a port that supports it, no it probably can’t sadly. Usually new HDMI standards require the device to actually be compatible with it.
Current 4K TVs are capable of playing games in 60hz @ 10-bit HDR, but this spec exceeds the actual throughput of HDMI 2.0 causing dropped frames and unreliable performance depending on the cable. HDMI 2.1 also supports Variable Refresh Rate. Since 4K adoption is spreading wildly due to the inexpensive manufacturing of monitors, these are likely to be the greatest reasons for the new format right now. It also supports 8K resolutions at high framerates as well.
However, keep in mind the HDMI is, as C-Net puts it, a “dumb pipe.” Specifications just provide a guarantee of what kind of performance you should expect from an HDTV and its cables. So, it’s entirely possible your current hi-speed HDMI 2.0 cable and television can deliver 4K at 60f in HDR, but without the specification demanding it, there’s no way to tell for sure.
I just got done making a project with UE4 that was intended to run 4K in 60f HDR and I did run into issues with some cables and monitors. The good news is the monitor and cables that were eventually purchased worked fine. In the future with 2.1 solidified, there wouldn’t be any more doubt.