To be honest i'll never be moving on to 4k, there's just not enough of a difference to be any use to me, the actual graphics difference isn't that great a leap to make it worth it, and the only real bonus you get is the higher refresh rates, which in turn give higher fps, but to be honest that only helps if you're playing competitive gaming, and even then there was a video i watched a while back that proved a high refresh rate 2k screen is better for gaming than a 4k one.
Primary Desktop:
i7 7700,k NV1070 8GB, 16GB 3200mhz memory, 1x 2TB Hybrid, Win10.
Secondary Desktop:
i5 4760k, NV960 2GB, 16GB 2333mhz memory, 1x 2TB Hybrid, Win10.
Primary Laptop:
i5, NV1050 4GB, 8GB memory, 1x 1TB HDD, Win10.
Secondary Laptop:
i3, Intel 4000 series graphics, 6GB memory, 1x 500gb HDD, Win8.1.