Should Diamond OA be viewed as a threat to librarians?

Open access has become a growth opportunity for publishers with the “Gold Open Access APC” model and the hybrid model. During the period 2012-2015, these proposals generated a lot of lively discussions. The Scientific Board of the CNRS (National Center for Scientific Research in France) Institute for Mathematics (INSMI) has made some recommendations to French mathematicians for their publications asking them not to choose the author-pays option for open access, especially for hybrid journals, and not to include publication fees (APC, author processing charges) in funding requests. The rejection of the author-pays model by French mathematicians gives a boost to the development of other economic models of scientific edition, especially the Diamond OA (Gold OA without APC). This new model requires new skills from librarians. In this paper we present the Diamond OA publishing model, with a stress on the French situation in mathematics, and then explore the problem of how this model could impact libraries and librarians. Everybody says that Open Access is a real opportunity for libraries but we would like to be a little provocative: is Diamond Open Access a threat to librarians?