This seems to be about article text, or mainly about article text (articles imported from other wikis and so on).

The plan for the structured data project is to create Wikidata properties for legalese, install Wikibase on Commons (and possibly other wikis which have local images), make that Wikibase use Wikidata properties (and sometimes Wikidata items as values), create a new entity type called mediainfo (which is like a Wikibase item, but associated with a file), and add legal information to the mediainfo entries.

Part of that (the Wikidata properties) could be reused for articles and other non-file content - the source, license etc. properties are generic enough. However, if we want to use this structure to attribute files, we would either have to make mediainfo into some more generic thing that can be attached to any wiki page, or abuse the langlink/badge feature to serve a similar purpose. That is a major course correction; if we want to do something like that, that should be discussed (with the involvement of the Wikidata team) as soon as possible.