Madonna and Mary J. Blige aren’t all that’s coming from the American Music Series in 2016. Also now officially in the pipeline is a book on T Bone Burnett, the mystic auteur behind “O Brother, Where Art Thou?” and the Robert Plant/Alison Krauss collaboration Raising Sand, among many other Americana signposts. Scheduled for fall 2016 on University of Texas Press and tentatively titled “The True True Identity,” it’s written by the Chicago-based critic Lloyd Sachs. Upon receiving word this week that he had attained final approval (a process that can indeed be something of an ordeal), Lloyd marked the occasion as one does nowadays — on Facebook, with the post below. Congratulations, Mr. Sachs.