Wikipedia Pinyin Chinese (coded for now as cmn, Mandarin Chinese): Here's a proposal that I think needs some serious discussion. Please read the discussion on the linked Meta page. 

Arguments against:

• No separate ISO 639-3 language code
  
• It is proposed that this can be handled with a script converter, per (for example) T193366.
  
• One respondent objected to such a project taking manpower away from other Chinese-language projects.

Arguments supporting:

• Extremely widely used, and much on-line work in Chinese happens in Pinyin, not in ideographic characters.
  
• Proponents state (I cannot confirm) that there are many people who are "illiterate" in Chinese, not having mastered 3000 characters, who can potentially contribute to such a project. If so, that is closer to the ideal of creating projects that "anyone can edit".
  

I would also note that several other Chinese projects use Romanized Chinese. (All the min-nan projects are exclusively in Romanized language—see Wikipedia here; Min Dong Wikipedia has pages in both scripts.) 

If this project is deemed eligible, I'm pretty sure that it should not be coded with "cmn". (I can let it stay that way in Incubator for now, or give it a q-code.) Test has 250 mainspace pages, and has been active periodically. Last period of substantial activity was during summer 2017. 

I am going to hold back my opinion on this just yet.