As an update to this. Brian's book actually quotes part of Jay Miner's June 1988 Amiga User International interview re. the follow-up chipset to OCS from 1986/1987. So that puts it's design/development prior to the Amiga 500 and 2000 being launched and it doesn't sound like it has anything to do with what became ECS either.
To quote Jay, "Commodore now has a high resolution chip set of Amiga chips that I worked on when we were with Amiga in Los Gatos. These chips use video RAM and can produce a very high resolution ten twenty four display..."
The chips may not be in that case featured in the photo, but it sounds like they do indeed exist -- somewhere. At very least, the designs.