From the looks of it, yes. It appears to be co-op in all three stories. I'm happy about that since 100% of the time I played RE5 was with my brothers or sister and we had a blast. Probably my favorite co-op game as we put more than 100 hours into it total. RE6 is gonna be one of the only games I get at launch since I can already tell it'll be worth the price.
I am the morning sun, come to vanquish this horrible night. "Soma can believe it's not butter."
The AI was pretty awful for me in Resi 5, it ruined an average game, much worse than having Ashley with you in 4 because you could at least tell her to stay put and not get in any danger. Sheva runs around like an idiot wasting ammo and herbs. Everyone knows this, in fact I'd say it broke the game, almost unreleasable.
Pro mode with AI Sheva is just possible but absolutely no fun. It's the definition of frustration.
Co-op with a friend is a different matter though, fun, but not in a scary way. I'd say it looks like Capcom have given us another partner, though I'm hoping you have a choice to play with one or not.