We are living in an age in which digitization will connect more and more physical assets with IT systems and where IoT endpoints will generate a wealth of valuable data. Companies, individual users, and organizations alike therefore have the need to control their own physical or non-physical assets and data sources. At the same time, they recognize the need for, and opportunity to, share access to such data and digitized physical assets. This paper sets out our technology vision for such sharing ecosystems, reports initial work in that direction, identifies challenges for realizing this vision, and seeks feedback and collaboration from the academic access-control community in that R\&D space.