The Sony a7s III has likely been further delayed because of Coronavirus, which means it needs to be that much better.

A solid argument can be made to say that the Sony a7s III is the red-headed stepchild of the family. I mean, Sony has been saying that it’s coming for over two years now. With the delays caused by COVID-19, and the rest of the industry catching up or superseding what Sony can do with most video options, the Sony a7s III will need to be just that much better.
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https://www.thephoblographer.com/2020/04/09/will-we-ever-get-the-sony-a7s-iii-these-features-are-a-must-have-now/