Use Community for Sharing within the same Tenant
Ability to use Community to share data from different namespaces within the same tenant.
An example would be a connected services customer who is storing data for their customers within their tenant. Data is segregated by Namespace. These customers may want to share subsets of data with each other. So the Community would contain 1 tenant and data from different namespaces within that tenant, and users of that tenant (who may only access the data through an external app like Power Bi or the Connect Service provider's own Portal).