4K at 60Hz for $1k+ does not "compute" and is not a one size fits all for all users; speaking for gaming here. Graphics applications and photo/video editing, it's all yours!
A 1440p 120Hz/144Hz gaming monitor of your particular flavor (IPS, TN, AMVA/Flat, Curved/Single, Multiple, etc; You get the idear folks) is of a more logical and performance oriented enterprise for the foreseeable future for gaming and has been since the first 4K display that debuted as a "gaming" monitor.
1440p gaming monitors come in under less than 4K "gaming" monitors, traditionally. BETTER performance, no questions asked and are less taxing on your GPU(s). For those with higher-end GPUs, crank up those settings to Ultra and Max, ESPECIALLY with the GTX 1080 now in action and the soon to debut MONSTER, Pascal Titan X.
No matter how you slice it, SLI it (your rig)... 4K at 60Hz is still 4K stuck at 60Hz. No thank you.