Hello.
The question in the subject line, asked by the Aramaic expert on the Assyrian thread, has been floating in space (and making me curious) for years. To my knowledge, we have never had a good answer. So I'm taking the opportunity to attempt discussion of it.
It seems to me it would be good to get at some approximation of an answer. For example, Milos just mentioned Cora, an indigenous Mexican language with about ~10,000 speakers. Thinking of a *Wikipedia* in that language seems to me a complete waste of time. Statistically, it would seem it could never recruit more than a handful of volunteers, and it would not have a reader base, nor ever offer even a modest genuinely-useful corpus of up-to-date, encyclopedic knowledge.
It makes absolute sense to document the Cora lexicon (on major Wiktionary projects, i.e. in other languages), to curate any extant literature (on the multilingual Wikisource), to record and document live speakers (and any folklore) on Commons, etc. But I think this language won't ever achieve an encyclopedia, and I think it is unhelpful to pretend otherwise.
You may disagree, perhaps. What I am interested in hearing the committee's opinion about is the general question: can we identify the criteria for a minimally-viable Wikipedia?
I will take a shot at a very rough, partly arbitrary definition of "minimally-viable Wikipedia": a wiki community commanding sustained participation from at least 5 very active editors and at least 20 active editors, and able to reach 20,000 non-stub articles in under 10 years. (many other definitions can be offered.)
It seems clear, for example, that 1 million literate speakers of high average education level, stable orthography, and available secondary sources and higher education in that language (e.g. Estonian) are definitely enough to sustain such a community.
But there's still a lot of room to ponder -- would 500,000 speakers also be enough, provided the other characteristics are in place? Would 10 million speakers be enough, if there's no higher education or secondary sources in a given language? Etc. etc.
Langcom is probably the densest concentration of expertise able to approach this question. Is the committee interested in thinking about it and maybe working towards some working recommendation/guideline? (I don't think it necessarily has to result in any policy change for LangCom. It may just be a useful guideline for interested volunteers/communities to compare themselves with, for example.)
Cheers,
A.