The problem with any high resolution display is getting the process down, the easiest thing to do, and what you generally see is they either make such displays at very large sizes, like the 80 inch sets, this way they can use a current DPI standard and just make it bigger for more pixels, or they shoot for phones with the higher DPI but not higher resolution. They lest them hedge bets by being able to throw out many pieces that have dead pixels or fail for any number of reasons and still salvage some fully functional displays.
The problem for PC monitors is we get shafted right in the middle of that, so essentially we get everything dead last. High DPI goes to phones, high resolution goes to TVs. But on the other hand we do get some decent devices which strike a nice balance like the glut of 27 inch 2560x1440 monitors that can be had cheap.
The other problem that is coming to light is the fact that desktop monitors are becoming lower volume units. The fact is a ton of people just use laptops now, and many of them are even switching to tablets. So this means even if the display makers are capable of making say a 4k display at 30 inches, they might just feel they wont have enough volume to try it. The might just make that panel and cut it into 4 for 15 inch laptops. This is all the more reason that you should start thinking hard about the HTPC because their may come a day when its better to buy a TV than a desktop monitor.
We have seen this cycle of obsolete products happen over and over. The average consumer is not a video or audio phile, they dont know how to use a computer or game, they pretty much dont care about anything but, can I get on face book.
I would love to see 4k in a 32 inch I would think of it like a big bezeless eyefinity display. Of course we have yet to see how this will perform.