I like these vague questions... :)

I'd think it would be appropriate to spec out how these features should work and get a consensus on such a plan. Think about questions like:

* how is it represented in the wikitext? I.e. do I categorize a picture with [[Category:Dog]] or can I also write [[Kategorie:Hund]]?

* how should this be displayed on a page?

* what about subcategorizing? How does this work?

* is it only about categories? What about image descriptions?

* what about the plenty of data that is already in Commons? Can this be reused or replaced?

etc.

There are plenty of questions that are not clear when thinking about Commons. Commons is the second largest WMF project, and growing with an increasing speed. Features like Wikibase's sitelinks, labels, descriptions, and aliases could be possible to be reused on Commons, I would say, but this only answers a few of the questions that arise from changing a complex socio-technical project like Commons, and it is obvious that this should happen within the Commons community and be discussed in the community.

Or, put differently: I don't know enough about Commons and its community. If there is something like a RfC-process on Commons, it should probably be started and a goal drafted of what is actually desired.

Our own focus for the first year of development of Wikidata is with Wikipedia, as was always communicated, but we are aware that there are a few low hanging fruits to be gained for other projects once Wikidata is fully functional.

These are just my own thoughts. I hope that helps.

Cheers,

Denny