Answer is in the dev last ci-en post.
Hehos the next 2 scene extension, indicating that would make about 1/3 of the extra h-scene content he has planned for the game. And he mention that it's taking time since he's also working on an append as well as the next work ( ps : that what I get by tanslating the Japanese text with translating tool. I don't want to bring false hope by making it a reality. Wait for someone to confirm).
But if so, there no info about the append. If you take all the extra scene extension to make 1/3 of the total, then you'll have about 24 - 30 extended scenes (or possible new scene in it) and probably some new clothes / clothes coloring.