I will admit I've thought of doing something like this, re-doing the old 'takes on the galaxy' threads. But...honestly, the state of 40k play right now makes this seem rather silly and difficult to me. I mean, first off, even just ignoring the allies matrix and what changes and options that brings but then you also have the fortifications and the now rather extensive super heavy list as well and those additional formation things from the advent releases.
The idea of balanced play is pretty shockingly skewed right now, and of the local tournies I attend the overall meta is quite different because of how they're choosing to address the question of those rules.
Basically, looking at it all, I sort of decided that most answers are either far too general or that to properly cover the possible threats creates far too vast and unwieldy of a response.