It seems that we've hit a wall when it comes to mobile screen resolutions - not that the technology isn't there, it's the purpose that is missing. Sure, VR enthusiasts (15% of voters) are excited for 4K 2160p screens since virtual reality headsets need all the pixels they can get. However, as some of you rightfully pointed out, Sony has no interest in mobile VR since it will compete with the PlayStation VR. Samsung has no such qualms and works with Oculus (both on the Rift and Gear VR) and seems to be working on a standalone headset. Asus and others are allegedly working on standalone...
Source: http://www.gsmarena.com/weekly_poll_results_1080p_screens_are_good_enough_theres_not_much_need_for_4k-news-23480.php