It seems that the magazines from 2013 in the Watchtower Online Library will contain pictures. (http://wol.jw.org/)

In the Online Library, select Publications, then either Watchtower or Awake, then 2013. You will see the January issues of all our magazines. Click on (almost) any of the articles in the issue you choose, and you’ll see pictures! For the moment, this seems to be just for the English magazines, but certainly other languages will eventually have pictures and illustrations too.

I confirmed in the Czech, Greek, Hungarian 2013 magazines have pictures. So this seems an across-the-board fact of pictures in wol.jw.org magazines from 2013 on.