It is a bit unclear to me what exactly is being proposed. That every app exposes some kind of common standard API that can be used to link with other apps? Take their twitter example. How would “taking your followers with you” work in practice? I can imagine some sort of indirection layer that associates each user with their respective provenance domain + an update protocol if the provenance changes, but there are likely challenges when it comes to scalability. Who is going to design/mandate these interfaces and where will they be applicable? What’s the criterium?