In XR domain, volumetric video is a well-known application of 3D reconstruction. But 3D reconstruction is also used by most XR devices for inside-out 6DoF tracking based on SLAM, and the ARCloud technology plans to distribute it in the cloud with 5G connectivity to provide large-scale multi-user XR experiences. How does this technology work? What are the benefits of the ARCloud, the technological challenges, and above all what are the future impacts of such technology on our society? Welcome to a new world, an augmented world!