CNET article:
Panasonic WXF991, VX981, W580, V380 and V180 Release Date, Price and Specs - CNET (http://www.cnet.com/products/panasonic-wxf991/)

Press photo:
https://www.flickr.com/photos/pauloteixeira/24113097791/in/dateposted-public/
I just fixed the link.

Press release:
Panasonic's New Camcorder Line-up Provides Videographers and Families with Everything They Need... -- LAS VEGAS, Jan. 5, 2016 /PRNewswire/ -- (http://www.prnewswire.com/news-releases/panasonics-new-camcorder-line-up-provides-videographers-and-families-with-everything-they-need-for-picture-perfect-recording-300199339.html)

Some videos:
Panasonic VX991 4K Camcorder Overview - YouTube
Panasonic VX981 4K Camcorder Overview - YouTube
[NEW] Panasonic 4K Camcorder WXF990/WXF991 Stunning Image Quality - YouTube
[NEW] Introducing Panasonic 4K Camcorder VX980/VX981/VX989 Series - YouTube

No sensor size specs whatsoever. 1'' would be impressive, 1/2.3'' would be typical consumer level equipment.

The Flickr link doesn't work too.

4K Ultra HD Video at 24/30 fps
1/2.3" BSI MOS Sensor
20x Leica Dicomar Optical Zoom Lens
Twin Camera & Wireless Multi-Camera
Tilting 0.24" EVF / 3.0" Touchscreen LCD
5-Axis HYBRID O.I.S.+ and Level Shot
In-Camera 4K Cropping and Editing
Built-In Cinema-Like Effects
Capture Stills from 4K Video Frames
HDR Movie Mode

Typical consumer level then. I will never take 1/2.3'' as a serious sensor size for 4K. The AX100 and X70 still wins in sensor size regard.

Friend just bought the VX870, not very impressed by many of the features that were changed, hope this new model has improved on the VX870, otherwise the Sony AX53 is just going to kill it, just as the AX33 killed the VX870.