If XLR inputs, built in ND and general "video ergonomics" are of any concern to you, there's no need to wait.
If 4K is sth you need or you also need to take stills with your camera, you don't have to consider the C100.
I think those two cameras make it easy to decide between.
A7s vs 5DIV and C100 vs FS5 would be tougher.