So, this time next year, we'll have to deal with hordes of people who joined the project because of the book quoting it as policy in discussions when the relevant policy has been updated. Boy, I'm cynical.
I'd tend to agree. We might even have to create a whole new disclaimers/guideline explicitly saying that Wikimedia didn't endorse this book and that quoting it as "the truth" doesn't mean squat.
If the book is any good it'll point that out itself, along with the fact that this is true of the policy pages on Wikipedia itself.
In that sense I could see the book going two completely different ways - it could focus on quoting policy pages as written, or it could instead focus on the de facto power structure and the concept of "ignore all rules". The latter would be much more interesting.