Install Venice Unleashed on a mid-range or better PC. Spend 20 minutes setting up a local Conquest match on Caspian Border with 32 bots. It's the closest thing to a "BF3 single-player expansion" we'll ever get.
Bots rely on pre-calculated paths to navigate the environment. Stick to vanilla maps like Caspian Border , Operation Metro , and Grand Bazaar , as these usually have the most refined community waypoint files. battlefield 3 offline bots mod