Considering they are almost 3x the price of the 1440p 165Hz Gsync monitors, surely they are going to be less popular than those?
4K is itself a powerful incentive. It's a consumer standard, unlike 1440p. In time, I expect these monitors will end up in the same niche as high-refresh 1080p monitors. But I've just watched this video
which says that the monitors only come with HDMI 2.0, not 2.1. And that's a longevity issue, because HDMI 2.1 implements variable refresh and HDMI works better over longer cable lengths than DP.