I was able to see the new Sony a7S at NAB. It is a full frame, 4k video camera that looks almost identical to the a7 and a7R. Its full frame sensor does not use pixel binning or line skipping, so aliasing and moire patterns should be a thing of the past. Its low light capability is impressive with a maximum ISO of 409,600. You can see a demonstration here: Sony A7S: Low Light Demonstration. 

Happy Shooting!