Death of the monograph?

We hear a lot in publishing circles about the decline of the monograph, but perhaps less about what might replace it. In an article published this month in The Journal of Scholarly Publishing, HUP's Executive Editor for the Humanities Lindsay Waters, a frequent contributor to conversations on the future of publishing, imagines a world in which the "well-wrought, slowly gestated essay" replaces the monograph as the scholarly item of record, at least in the humanities. The article is not yet online, but see Scott McLemee's summary of and response to the idea in his column at Inside Higher Ed. Waters addressed similar issues in a 2007 IHE column titled "A Call for Slow Writing."