Scaling Trust on the Web, the comprehensive final report of the Task Force for a Trustworthy Future Web, maps systems-level dynamics and gaps that impact the trustworthiness and usefulness of online spaces. It highlights where existing approaches will not adequately meet future needs, particularly given emerging metaversal and generative AI technologies. Most importantly, it identifies immediate interventions that could catalyze safer, more trustworthy online spaces, now and in the future.