This issue of sufficient participation does appear of rising concern to wikipedia's survival following our first community peak in ~2007 and has brought my attention back to the project after some years of inactivity. In my opinion, revisions to the interface will be central to eliciting more non-meta edits from casual users who need not be fully educated on the code syntax or policy behind the curtain.
Is there an active conversation I've yet to find that is focusing on this issue of editor population over time?
The Percentage of Maximum statistic shown here
http://stats.wikimedia.org/EN/TablesWikipediaZZ.htm for "active" editors with over 5 and 100 edits this month are ~80% and ~90% respectively down from their peaks in 2007. These stats appear to be trending downward, but not steeply.
The article count growth rate stabilized and continues to decline. I don't yet find recent numbers on vandalism.
I would also like to see numbers extending this work on strategy from from 2010 to the present :
[[en:user:here]]