What is the future of grey literature? The 2021 survey and the panel discussion provided some interesting ideas, opinions and expectations; two-third of the respondents to the survey agreed that “in academic institutions, the affirmation of open science and open access principles significantly favor the production, publication, and retrieval of grey literature”. But it remains uncertain if the new paradigm of open science is an opportunity for grey literature (more grey literature, more visibility and impact of grey literature), just another challenge (issues that need awareness and further action) or even a threat. As one respondent put it, “the major question is if it is still grey literature (…) published grey literature is no more grey”. One reason for this situation may be the confusing definition of grey literature which is most often, especially in systematic reviews, considered as unpublished and non-reviewed research which is not exactly the meaning of the concept in library and information sciences, where the focus is on issues related to the dissemination and the acquisition of this part of academic production. The paper tries to assess some essential aspects of the development of grey literature in the era of open science, such as production and dissemination, evaluation and processing. The paper presents a review of recent, relevant studies on grey literature and open science, based on a search in the GreyNet portal, in the Web of Science and Scopus, and completed with results from the Dimensions and Google Scholar academic discovery tools; the paper will include recent reports and initiatives, and it will build on a synthesis of our own former empirical research on grey literature. The results of the literature review and of the synthesis of our empirical research will be presented in four sections: the concept of bibliodiversity (production); the development of open repositories (dissemination); the transformation of research assessment (evaluation); the application of FAIR principles (processing). Some leading questions: Which is the common part of the concepts of bibliodiversity (Jussieu Call) and grey literature, and what does this mean for the future of grey literature? Which are the issues of grey literature in open repositories, and how do repositories impact the dissemination of grey literature? How do the recent initiatives for a new system of research assessment affect the grey literature (San Francisco Declaration DORA, European Commission Scoping report, OSEC Call of Paris)? Are the FAIR principles relevant for the processing of grey literature, and if so, which ones and in which way? The paper is a scientific contribution to the analysis of the development of grey literature in the academic research environment of the 21st century. It is also a rejoinder of the 2021 panel discussion on the “Next Generation Grey”. We’ll try to sum up what is known about grey literature and open science and to make clear what is questionable and what needs more insight.