The arXiv preprint repository, founded in 1991, has become the de facto dissemination platform for physics, mathematics, computer science, and increasingly other quantitative disciplines, hosting over 2.4 million articles and serving millions of users worldwide. In mid-2026, its governance will transition from Cornell University Library to an independent nonprofit entity governed by a board of directors and supported by private philanthropy. This article provides a data-driven examination of that transition, placing it within the history of the repository and the broader political economy of scholarly communication. Drawing on public submission statistics, moderation records, documented controversies, and historical precedents from academic publishing, we identify six structural risks: opaque governance, centralized editorial control, financial unsustainability, systemic bias, erosion of scientific pluralism, and potential mission drift toward privatized gatekeeping. We argue that the moment before institutional inertia sets in is precisely when the research community must insist on binding transparency and accountability mechanisms. We propose a set of concrete safeguards---a community-elected advisory council, mandatory transparency reporting, an independent moderation ombuds, a free-access charter, and periodic external audits---that can preserve arXiv's identity as a public good without compromising operational agility. The manuscript itself has been submitted to arXiv as a real-time test of the moderation system's openness to self-examination.