Nothing confirmed about offline modes as of yet, but I'm hoping at least for an online/offline private match feature to play around in with friends and get to learn the maps better. Perhaps Rent-a-Servers will make a comeback, but I don't necessarily prefer them. Bot mode feature would be great too, but I just don't expect that mode to be in the game, simply because it seems most shooters don't ever have this feature. Most recently, I can only think of Black Ops' Combat Training and Killzone 3's BotZone, but I suppose it could happen in Warfighter.
And while it isn't a game mode per se, I would like to see online multiplayer 2-player split screen. With Warfighter introducing 2-player Fire Teams, this feature would be great because you and a friend could play together on the same TV and the same Fire Team, similar to Call of Dut, having your Gamertag and your friend's or guest's Gamertag(1) as your split screen buddy.