The years of 2018/2019 will be very interesting for products with full frame 4K 60fps video/photo cameras. At this moment there isn’t a single camera that could handle 4K 60fps at no crop in full frame. You do have a Canon 1DX Mark II, but the crop factor while shooting at 4K 60fps is 1.4x. If you can accept that and the price tag of a proper professional video camera, then be my guest.
One of the most promising manufacturers of mirrorless cameras Panasonic has announced their own new line of full frame cameras in the year 2019. They’ve only put out some basic information about the two cameras. Why, because they are still in works and they don’t want to give too many hopes and then not achieving them. Why these two cameras matter? Because they will put a new gravestone for bigger companies such as Canon and Nikon. A lot of videographers are looking for photo camera with impressive video quality. Why should you buy a Canon or Nikon camera with very limited video capabilities, if Panasonic is the best bang for the buck? Unless you are primarily a sports photographer, then looking towards Canon or Nikon cameras is more logical.
What will the future Panasonic S1R an S1 include: Both cameras will feature in-body image stabilization (IBIS), 4K 60p video recording, dual card slots. Making it the perfect mirrorless camera for run and gun situations and other production work.
On the other hand, Sony did want to announce their own newest mirrorless camera but withdrew after Panasonic announcement. They probably had the newest Sony A7sIII in the sleeve killing the Nikon Z1 and Canon EOS R, but not good enough to withstand the Panasonic S1R and S1 cameras. Now we wait till 2019 when they update their equipment:)