Even without 4K, I'd probably buy it for 1080/96p, factory flat color profiles and master pedestal.
Here's a new video from Panasonic showcasing these features, followed by some Panasonic marketing copy:
http://youtu.be/oMnh6wNfmF0
"The new Panasonic GH4 is a great tool for Indie Filmmakers.
With its new CineLike D and V features you will be able to record videos with up to 13 stops of Dynamic Range with a cinematic roll off.
It also features the Master Pedestal option, which will lift your shadow areas, giving you an even better Dynamic Range.
That means that you wont have to worry about your Highlights or your Shadows, because the new GH4 will deliver a beautiful, cinematic image.
Use it in 96fps 1080p, to create a wonderful slowmotion, or even in 4k, to deliver a high-end, powerful image!"