Does anyone know of a recent book that describes some of the efforts and thinking about the future of code?

I don't know of any, but there is The Future of Text which includes essays by a number of familiar names including Alan Kay.

I don't think any exist. It's an interesting idea for sure. It might be a bit challenging to have a cohesive narrative for a book.

My book-in-progress aims to touch on this (though, alas, you'll have to wait a bit for it to come out...) https://arbesman.substack.com/p/the-magic-of-code