How long we got? Give me till the end of this generation and I'll take Killzone. It has a single player and will still have copies out there years from now. I think it will slip over 3M.
Titanfall will basically be over when Titanfall 2 is released. No one will be buying the first one after that point. I also think it will be perceived as something of a flop, given the hype. Assuming it releases at $60, I don't see it reaching 3M. It's a crowded market that it's trying to break into and I think the mecha aspect will turn off some of the casual FPS fans. It's not going to be as big as some people think.