What's after 1080p?

From CES..
82-inch Sony prototype display 2160p (or 4x)

I have wondered and people have asked me, "OK, what comes after HDTV 1080p?" This question is about screen resolution, currently the best resolution for HDTV is 1080 lines on the screen updated progressively. I found that Sony and others are showing screens with 2160 lines.

2160p is also called "Quad HDTV" since it displays four times the number of pixels of 1080p. Quad Full High Definition (QFHD) is the next step in high-resolution display technology.

To avoid the technical stuff, its better than HDTV, like HDTV is better than standard TV (which has 480 lines). It may take ten years before its affordable, but it sounds cool.

Sony shows 2160p prototype