That's not the main thrust of the article, it's about a class of apps like Yojimbo, iTunes and iPhoto that abstract away the underlying file system so that even the concept of saving data goes away.

This goes beyond auto-save. He's talking about auto-first-save, or just remember-what-I-was-doing mode.

The point of the article was not that applications should have auto-save.

As I read it, the point is that our hierarchical filesystems are not an especially good abstraction for organizing many types of data, and that applications should provide users with better abstractions in more cases. It appears to be a response to The Case Against Everything Buckets (http://news.ycombinator.com/item?id=460274).