If textbook publishers hear the message “more nonfiction” instead of “coherent curriculum” then the effort will have come to little. Slapping random nonfiction (duly tested for complexity) into existing textbooks will be no more effective than the reading of random fiction has been.
Hirsch doesn't seem to understand the plan being implemented. There's no pretense of going from standards to curriculum to assessments of understanding of the curriculum. There are the standards, there will be assessments of the standards -- of the enumerated standards, not Common Core or anyone else's commentary on the standards, not of knowledge of the recommended texts. There will be curriculum, textbooks, etc. aligned to the assessments. There will be increasing emphasis on online assessment which is detached from the rest of the curriculum, e.g., sign up for this module of you need reading social studies 4. There will be increasing use of regular diagnostic tests at higher grade levels for specific reading standards, e.g., this group needs to work on comparing structured poems to free verse, while this one works on analyzing how a dramatic production of a work departs from the original text. There will be standards-based assessment, where the standards are not "understandings," "skills," or "knowledge," but tasks.
That's the plan, and it ain't a secret.