@Miranche: I've been thinking a lot about this problem, although I would never attempt to implement this in MediaWiki (would use Xwiki or Gitit wiki, if I ever get around to it). The killer features here would be to (1) integrate the data stored locally (bibtex or Zotero) on the user's desktop, (2) to integrate the citation form into the visual editor. I'm afraid anything less will just not work from the user's perspective — it will just not be worth the hassle compared to pasting a URL into Citoid. For (1), a program would run locally on the user's system. That program would send all local bibtex or zotero records straight to the wiki server and link those records to the user's account. That way each user has their entire personal library always available on the server. When the user adds a citation from their personal library to an article, that citation is automatically added to a global library for the wiki (with the option of uploading an associated pdf or other file), which will be shared by all users (the record in the user's personal library will also be flagged as "shared"). I'd store and parse the data using using Semantic Cite.
We'll now need a citation picker in the visual/2017 editor. The picker will access three distinct "libraries" of bibliographic records: (1) the records already cited in the article; (2) the records from global library; (3) the records from their personal library. The picker's search interface will show matching records from (1,2,3), in that order. Alternately users may paste a raw url or bibtex code and cite a source that way (which will then be added to the global library). Implementing different citation styles would also be essential.
So yeah this would be a pretty big project for one person, but probably doable. It would certainly be a killer extension.