I think you're right on all accounts. The adapter to let the old lenses work on the new bodies is the thickness of the pentaprism on the old camera. It's designed to keep the geometry of the stuff that got removed when they went mirrorless.
A lightly used A-mount (like an A77) is an intriguing thought...if it had a kit lens, then my kids could keep using the a57 til it failed completely.
A lightly used A-mount (like an A77) is an intriguing thought...if it had a kit lens, then my kids could keep using the a57 til it failed completely.