We will have to wait til Photokina to get our two new big Flagship cameras. Based on the rumors we got so far those are the possible specs:
GH5:
16 MP sensor (Due the Kumamoto sensor shipment delay Panasonic may decide to use the 20MP Sony sensor instead and delay the GH4 launch by a bit)
4K 60fps
new image processor delivers best image quality of all Panasonic cameras
improved AF
E-M1II:
20 MP sensor
4k 30fps
improved image stabilization system
Handheld high resolution mode
dual SD card slot
improved AF
So the question now is….
