4k displays are available for medical analytics now. If my calculations are right Intel talks about 4.6k for 24'' and 5.7k for 30'' (12 megapixel with 24'' and 18 for 30.)
Have to take a look at it before I can decide. I have doubts, too.
EDIT: 4k on a 27'' monitor gives about 175 ppi.
Intel is actually talking of 3840x2160 ("double HD"), which for its example of a 21" monitor comes out to 220ppi. The 24" and 30" are offered as typical viewing distances for a 21" screen, not as screen sizes.
So it is not clear that Intel is advocating that same 220PPI for larger displays, which might typically be viewed from further away. It might make sense to aim at a 3840x2160 or 4096x2160 maximum for the near future, to fit with "4K" video and with the current maximum resolution modes of the DisplayPort and HDMI standards.