I believe a good chunk of the sales are clearancing out last year's model as the units announced at CES are finally shipping. Case in point, I picked up four LG 27" 4K IPS displays for $250 USD a piece and they're good units thus far. With pricing like that, the older 1920 x 1080 and 2560 x 1440 units are feeling downward pricing pressure. What is driving the new models to market are newer DP 1.3/1.4 controllers, HDR, 10 bit panels and higher resolution (see the 5120 x 1440 unit in the news). So basically if you don't need/want the bleeding edge, it is actually a fairly good time to get a display
Next year we'll again see a similar revamp of display product lines as HDMI 2.1 starts to make an appearance, even more higher resolution units and hopefully the HDR specs iron themselves out into some conformity.
Dual Opteron 6376, 96 GB DDR3, Asus KGPE-D16, GTX 970
Mac Pro Dual Xeon E5645, 48 GB DDR3, GTX 770
Core i7 3930K@4.2 Ghz, 32 GB DDR3, GA-X79-UP5-Wifi
Core i7 2600K@4.4 Ghz, 16 GB DDR3, GTX 970, GA-X68XP-UD4