Hello,
I think it is important that you discuss structured data for Wikimedia further in a language version before you introduce it in a language version. I dont know how high the openess for that topic is in for example the German Wikipedia. Can you please tell me what the distinction of this concept to a system using categories. From my point of view this is an important question after there is only acceptance if there is an understanding of the advantages. I am interested in metadata and I think it is good if this is possible to add it in Wikipages, what is exists currenctly with different Templates and I prefer a concept where it is possible to write the Metadata in Wikitext and I wish that there is also a tool that helps creating metadata for pages and what uses a form. So I think here about a kind of contenct creator. The Wikidataqueryservice is an example of a interface where it is possible to type queries and to search for a property in the text if the functionality is known without using a form for search. This is something what I like.