One of the great disappointments this year in HDTV-land. Today I saw LG's $17,000 84-inch 4K display, showing a high-end travelogue: Other than black level(a little better but not all that much) the resolution was about equal to the 1080p Ultra-BluRay boxed travelogue discs which have been available for a year. So what's the big deal? The resolution on an 84-inch display is about equal to what you'd get with a high-end source on a 65-incher like mine and that is a genuine benefit, but will 4K become the norm? If the cost gets down to what we now pay for 1080p, why not? But at the premium price being ask for today? Gimme a break.
There is little advantage to the 4K comparing to the 2K, especially if the 2K is compressed to the same bit rate as the 4K. As the displays approach 100" and more, the 4K becomes more justifiable. However, there is a trend towards high-density displays. One will see many new smartphones coming with the full 2K resolution next year and 4K computer monitors too . If pocket device has 2K then one can ask, why not 4K, or even better 8K, for TV displays.
8K in particular opens possibilities for scenarios going beyond the current TV viewing, e.g. immersive curved displays.