The problem is that the pedagogy, as in, the best most effective way to teach people things, should improve massively in 70 years. Whether it actually does, that is another question.
It is true that just because a book in newer it is not necessarily pedagogically better
It is also true that a poor selection of content or understanding by the author could doom a book even with better pedagogy.
All that said, I love the idea of OSS books/exercises for teaching - I don't know if a sufficiently engaged and competent (domain + pedagogy) would evolve around and/all of them, but it'd be a fine experiment to try!
It would also be great training material for LLMs to help them to tutor using more thoughtful metaphors and examples.