You can't have cake (low ISO) and eat it, too (Max DR). However, the better news flipside is that you GAIN a stop of DR at higher ISOs. So if you liked a GH4 at ISO 800, the GH5 will look the same or better at 1600. The early testers such as Griffin Hammond have confirmed this.
https://www.youtube.com/watch?v=BoYbqSxPWrA is a film he recorded with the GH5. And here he is, talking about making that film:
https://www.youtube.com/watch?v=3hCyiMhuRmkThe higher ISO performance improvement is for several reasons. They removed the AA filter for better color, contrast, and sharpness. They bumped resolution to 20.3 MP. They put all new color science into the camera, that does better demosaicing of the images. They incorporated a more efficient and lower noise sensor. The Venus Engine 10 processor is an order of magnitude faster.
All that means that cinematographers and videographers have more speed to play with, along with 4:2:2 video, anamorphic support, "open gate" video support, vLog L with monitor LUTs ($100 extra), full size HDMI port, USB-C port for SUPER FAST file transfers, a new audio input accessory with phantom power, 96 KHz 24-bit sampling, ALC on-off, two low cut filters, input level pads, mic/line switching, lots better 4K performance, higher slo-mo rates, and on and on... .
PhotoJoseph interviewed Sean Robinson, Associate Marketing Manager for LUMIX at Panasonic, on YouTube recently. They spent over 75 minutes talking about all this.
https://www.youtube.com/watch?v=68JJgDgML1g For all the buzz about the camera's video capability, though, it is also a very solid *stills* camera!
The new high resolution EVF is recognized by DPReview as the best viewfinder on the market.
There's a new AF point selector rocker switch on the back of the camera, AND you can still tap the OLED screen to focus, AND you get 225 AF points instead of the previous 49! Focus tracking has been greatly improved.
There's a new battery grip with all the right controls in the right places for vertical grip.
It's splash-proof, dust-proof, freeze-proof to –10°C.
It can do 18 MP '6K' stills at high speed.
With the firmware updates planned and announced already, we will get really great, fast computer tethering at last.
The menu system has been simplified and updated. (It was already great, compared to its competition!)
Five new and updated lenses were announced at CES. They all support the new Dual IS II system that is present in the G85. Included is the Panasonic Leica DG Vario-Elmarit 12-60mm F2.8-4.0 ASPH Power OIS which is a 24-120mm FF field of view equivalent. This is the pro complement to Panasonic's 12-60mm f/3.5-f/5.6, which costs less than half of the Leica design, and can be had for $100 when bundled with a G85. They updated the 100-300mm, the 35-100mm f/2.8, the 45-200mm, and the 12-35mm f/2.8 to include Dual IS II, better aperture blade design, and weather, dust, and freeze resistance features.
Panasonic also announced firmware updates for most older Panasonic lenses that have OIS, to make them compatible with Dual IS II.
This camera is a head turner for thousands of studio photographers and videographers and filmmakers. Panasonic has REALLY listened to the professional community over the last decade, and is including and developing features at an insane rate. I bought the GH4 for still photography AND videography, each of which is of equal importance to me. I'll eventually upgrade to the GH5 for the same reasons I got the GH4.