I'm not a developer, but it's been confirmed many times by the developers that there will be no Titan mode. There will be several other game modes, though, and many maps featuring cap ships. Some of them may have boarding action.
Edit: For one thing, the first release will feature a map called 'Escape from Hoth', in which the rebels control Corvettes and Gallofree Medium Transports and need to escort the transports to a hyperspace buoy. The Imperials will have TIE Fighters and Bombers, and need to intercept and destroy the transports.
"One of the bitches actually gave birth while she was attacking, and her puppies joined in on the carnage."
--the awesomeness that is Boatmurdered.