Sort of a tangential issue: Wikipedians should keep in mind here that whatever they do is a positive political and social/cultural act; there is no correct answer to this question.
Whether Chinese should be one language or diverge into multiple languages is somewhat similar to the question 180 years ago over whether the various Greeks spoken throughout the former Ottoman Empire should remain distinct, or be merged into a "common Greek", and perhaps also similar to the eternal disputes in France over the differences between the various regional dialects. If we, for example, say we support having a separate Wikipedia for a particular French dialect (which we do), but we oppose having one for a particular Chinese dialect, then we're making a rather odd political statement. Not that we can't do that, but it should be done on purpose.
-Mark