With IBIS this camera for me is back in the race. Would love to shoot with it in the dark, handheld or at most with a monopod, focus ring in one hand, the camera in the other: High tech minimalism.
Let's be realistic. Panasonic will never ever produce a full frame camera nor a hybrid super 35 camera. It's hard enough for them to establish their micro4/3 format. But they could bring a multi aspect sensor, that in 4k aspect ratio could come as close as the factor 1,8 to a full frame sensor (The Canon APSC format has the factor 1,7). Add the new, specially for the GH4 designed speedbooster to that and you enter full frame territory anyway.