We know a fair amount about three of Battlefront's multiplayer modes already:
On Battlefront's home page, there are three other modes listed as well, but all we know about them so far is their names, which are Cargo, Drop Zone, and Supremacy.
Even though that's all we have, I think we can probably determine a lot about what they will entail anyway. Cargo is probably a mode based around defending and/or capturing something, not unlike Capture the Flag, or perhaps even a Counter-Strike style bomb planting and defusal, with Rebels trying to destroy Imperial cargo and the Imperials trying to stop them.
Drop Zone sounds like it could be a Hardpoint style mode, with an area teams must secure that moves around the map throughout the game.
Supremacy is the one of which I feel the list assured in my assumptions. I can see it being a Domination or Conquest mode, with players trying to become the "supreme" team in dominating the map. It does seem like Battlefront should have a mode like this, since this type of game mode was the majority of both previous games in the series.
Again, all of this is speculation, aside from the actual names of the modes, but I think it's pretty reasonable speculation. If you have any ideas of your own, comment below and let us know.