They mentioned a tactical based objective Game Mode, and bot teammates (assuming that this hasn't been confirmed to be coming) would be really cool to see in it.
I think it should be similar to how Pavlov has its bots, where it's optional to have them, and they'll function as teammates if there aren't enough players.
I also think they should have voice lines, so the immersion is actually there, and you get the feeling of having actual teammates (look at the video to get the idea of what I'm talking about.)
I personally think that this would be really cool to see.