Well, it seems that we now have a solid day for the announcement of the Sony A7S III mirrorless camera. A listing has popped up on the B&H website, with no information, except for an event teaser image shown above and a notification of when pre-orders will begin.
The teaser image shows the A7S III logo with the slogan “Imagination in Motion”, reinforcing that this will be a more video-centric camera, like its predecessors. The date and time listed is July 28th, 2020 at 10am Eastern. This matches up with the date and time shown in the listing when pre-orders will become available.