In the top 20 of biggest Wikipedias ordered by traffic we find four languages that I find of interest: Russian, Chinese, Arabic and Indonesian. They are ordered as the number 6, 11, 16 and 17 in this list. All four represent large populations and consequently they all will go up in the rankings because all four are lively projects.
There is a relation between the number of articles and traffic. At the end of September, they had respectively 442 k (+2%), 266 k (+1%), 104 k (+3%) and 113k (+3%) in articles.
Russia and Indonesia have their chapters. Arabic is not local to one country and there is only a chapter in Egypt. Chinese is also spoken in multiple countries and it does not have a chapter in the People's republic but has one in Hong Kong and Taiwan.
When you consider that the annual growth in traffic is respectively 87%, 20%, 27% and 52%, you will recognise that they still growing. Compare them to the English Wikipedia its growth in absolute numbers is huge but expressed as a percentage it is not. I expect that these projects will benefit most from any measures that will make Wikipedia a friendly place. They need to grow to realise their potential and a healthy community is part of that.
Wikia has experience with several social extensions to MediaWiki. Does what they learned apply to our projects? Does it help in turning around communities that have gone sour? How do you introduce social functionality in our big projects ?
I expect all these four languages among the top ten Wikipedias in five years time. At the same time I expect the Wikipedias that currently make up the top 10 to continue their evolution and grow.