I'm sure you'll be able to participate in crewing everything from single seat fighters, to larger multi-person exploration/trading/combat ships, to massive capital ships!
What I'd like to know is will there be any compelling game play for people acting as the minor crew members (I know there will be NPC crew too) on these capital ships? Manning a turret (like every godawful turret level in any FPS ever) or staring at a sensor screen (like planet scanning in Mass Effect) doesn't sound like fun times to me.