Before I start, no, please don't say: "I hope the Gamescom footage fixes ALL the lore, visuals, and major gameplay mechanics" because I doubt they would make any major changes just after a month or two after E3. What i'm asking is: What do you hope to see in the Gamescom footage, based on what we've seen, not 'would like to see in the DOW game you wished you had'
Personally, I would like to see either a multiplayer gameplay trailer or just a multiplayer demonstration. I feel like Single player footage is either too scripted or passive when we know how much more intense and exciting the multiplayer in RTS games usually is. Plus it's where most of the replayability is (though I do hope the DOW3 campaign isn't as terrible as COH2's and has replayability too like in the Ardennes Assault DLC campaign).
I'd also like a change of scenery and a first glimpse of Orks