There is still PLENTY of knowledge that can be included into Wikipedia, but there are too few main editors to actually refine/expand upon the articles. To imply Wikipedia is "saturated" and that it now must grow linearly (because the past year reveals this pattern) is as ridiculous to say that human knowledge is perhaps saturated and must grow linearly because we have not collectively broken out of prevailing models of perception.

I believe that this flat trend (in a larger exponential curve that has yet to reveal itself) is a lack of initiative/participation for the moment that has zero predictive value of revealing the nature of Wikipedia's future growth rate.