At first, it seems that the needed data is already there: karma points are associated with tags, so it should be possible to set answering, voting, modding threshold based on the questions tags, though one would have to decide which tags are valid for a given question. And then there are subtopics: if I post a question on functional programming for instance, should a more specialized developer benefit from his clojure karma to gain privileges? Should it be a ratio? And then, if I update the question to focus solely on lisp, what happens of previous actions performed on now invalid privileges?