Images are seriously so blurry you could probably convince me that this was the next 1Dx Mark III.
In all seriousness though, as someone sitting here with his 5D3 in his hands, I really don't know if there's anything to legitimately make of this. The white "button" on the prism looks like it's the same sensor location marker that my 5D3 has, not a button. It's in the same spot, and there's no other obvious white markings on the prism if they happened to move that, so I'm pretty confident that's what that is.
I don't really see any evidence of the 7D mark II's lever around the joystick either, looks like an effect of the lighting that's drawing out the shadow of the joystick. So I'm pretty confident this is just a 5D3.
That said, it almost looked like there was a little white marking by the erase button on the bottom left, which my 5D3 doesn't have. Could just be an image artifact though. There's also a weird ridge above the left-hand controls, just under the menu button, but that could easily be an effect of the terrible lighting. So I don't really see any conclusive proof that this is a 5D4, and if it is, I don't see how we could get anything from this image besides "it's a 5D series"