The following is a combination of conjecture, rumors, and the old playtest rulebook melded together to get an idea of what we might be seeing in 6th edition. Its still all a little too early know yet, but looking ahead is a lot of fun.
So we heard earlier the following
Power Weapons AP3
Power Fists AP2
Chain Fists AP1
There are many units in the game that come with no close combat weapons. Kabalite Warriors for example. (Ive had my coffee by now). There were many things that we saw in the arguably squashed leaked playtest rulebook, and AP values for close combat weapons were a part of them. Now they do not necessarily match up with our current rumor set, however that would be expected in an early playtest book. (whether it was real or not is not the issue).
What is the point, is all the people very concerned that they will not be getting their 5+ or even 6+ saves in close combats. What I believe we will see, is something like the following
Basic CC attack AP-
Close Combat Weapons AP6
This seems logical, and is very similar to what was in the leaked playtest book. I also expect weapons like chainswords and some others to be AP5, and some weapons to even reach AP4. For those of you thinking worried about your nemesis force weapons being AP3, I believe you will be having to suck it up and live with it. It makes a solid case for adding a couple Daemon Hammers (possibly AP2) into your lists.
So putting all this together our charts could look something very much like this....
Basic CC Attack AP-
Close Combat Weapons AP6
Chainswords AP5
Power/ Force Weapons AP3
Power Fists AP2
Chain Fists AP1
Then there are some like Monstrous Creatures and Lelith Hesperax that ignore armour saves completely. I don't see these as needing to be changed, but adding a low AP value wouldn't matter much.