It seems the multi-aspect sensor feature is still not in use in the G6 if you look at the pixel sizes of the stills:
GH2: http://panasonic.net/avc/lumix/systemcamera/gms/gh2/specifications.html
"[3:2] 4,752 x 3,168, [16:9] 4,976 x 2,800"
GH3: http://panasonic.net/avc/lumix/systemcamera/gms/gh3/specifications.html
"[3:2] 4,608 x 3,072, [16:9] 4,608 x 2,592"
G5: http://panasonic.net/avc/lumix/systemcamera/gms/g5/specifications.html
"[3:2] 4,608 x 3,072, [16:9] 4,608 x 2,592"
G6: http://panasonic.net/avc/lumix/systemcamera/gms/g6/specifications.html
"[3:2] 4,608 x 3,072, [16:9] 4,608 x 2,592"
Even though the G5 and G6 appear to use the same sensor as the GH2, neither of them records 16:9 and 3:2 stills with a larger crop according to the official specifications.
So where does this often-quoted crop of 1.86× actually come into use other than when the GH2 shoots 16:9 stills/video and 3:2 stills?
Is there any proof that the G5 and G6 use this larger crop in video mode even though we know they're not using it in stills mode? Because otherwise it seems like the larger sensor of the G5 and G6 is no real advantage over the GH3.
Or could a firmware hack bring the full sensor area back into use?