Now, we are headed into the fourth phase of social media, where the growing market impacts of streams will begin to impinge on computing in general, so we will see streams become primary design elements of operating systems for computing and mobile devices. As this advance spreads, the premises of the earliest phases of social media can begin to be considered as layers in an architecture.
Old school blogs and other publishing models that create static web pages will increasingly be treated as an archive, or as a source for social objects referenced by URL, but where the URL is used to fetch the content and display it in the stream, just as today photos are being resolved in Twitter clients.
In the near future, all media types will be resolved in place, in the stream. This will create interesting issues with advertising revenues and other media control issues, but in the long run, ads and other metadata will be pulled along with the context-free slow media into the socially-embedded context of streams.