Digital object identifiers are an international standard for document identification:
https://en.wikipedia.org/wiki/Digital_object_identifier
The WMF could be a DOI registrant, and resolve DOIs in the form 10.NNNN.Qnnnnn for Wikidata items, or, say, 10.NNNN.en:609232908 for:
https://en.wikipedia.org/w/index.php?title=The_King_of_Rome&oldid=609232...
Where 's the best on-wiki (Meta?) place to propose this?