I got the following rumor from a new source:
Panasonic is working on a tech that make the big microlens cover 2×2 pixels. It can output 1/4 size picture by binning without any quality problem and each pixels can be cross type phase detection autofocus point to enhance the DFD.
One of the samples, is working on a sensor above 46-megapixel before binning, can output quarter-res at 128fps. Maybe the competitor of α7S III is coming ?