As of now, we know that we'll have a story-based multiplayer mode in Attrition and Hardpoint which tasks teams with capturing points A, B & C. However, we don't know much else at this point. It seems likely that we'll see Team Deathmatch, and it'd be a huge mistake to not have a capture the flag mode. Maybe we'll see a mode that's based on FFA where one player is a Titan, and the others in the match work to take them down. Whoever is in first place gets the Titan, or maybe the Titan randomly spawns and it's a race to get it! What other modes do you want to see in the game though?
I agree, CTF is a must have. It'd be nice if Respawn(or the community) came up with some type of sport in the game that could make it's way into playlist(like Grifball or Ricochet did in Halo).