These are some things that I believe would greatly enhance the game.
-Ability to create and upload custom badges, because I want to see angry marines and different factions.
-Full 3D camera, so we can see game play up close and personal. Like the trailers. You need that for 40k.
-Army painter in alphabetical order. Searching for an army can get very annoying. General better organization overall. Although the interface changes are improving. Now you can actually scroll down for instance.
-The implementation of matchmaking for annihilation modes, which may be difficult.
-The removal of the turret doctrine, or reinvention of it. I feel turrets have no impact on the game, and that only less experienced players go for them. Turrets cannot even be upgraded to deal withat heavy armor. thy are weak and I dislike seeing allies spamming the, only to have them all destroyed by a single dreadnought. Turret doctrine could perhaps add anti armor options, or reduce build time or something. But turrets do not have a significant role in the game, to require a doctrine. Especially with all the new cover systems.
I think that is all for now. Note that this is my opinion.
-Oh and you teased Necrons. You have to bring them in the expansion now. I eagerly await, because another thing DOW 3 needs is more races!