Is this RfC still reasonably up to date, or has time passed it by?
Topic on Talk:Requests for comment/Wikidata API
still up to date
Basically this is awaiting the author or another developer who is willing to put time into implementing it, so I'm marking it as abandoned - in the sense that without an active author who can work on it, it's dormant. Anyone else is welcome to take it up and reactivate it and post to wikitech-l when interested in working on it.
In addition to needing someone to actually write the code, this need some kind of buy-in from the Wikidata team.
Wikidata mostly agreed with the proposition, they just don't have the bandwidth to do it.