Forget a campaign mode - it doesn't need it and if they did add it.. it wouldn't be the selling point. Sins is successful for the mod-ability and the game-play, not the story. If they release SINS II with 64bit, full Multi-core support (can eat as many cores as you have), graphics overhaul, and revamp the UI.
It's like printing money for them.
I'd be ok without a campaign, as long as there is capabilities to make 'scenarios' or missions, with some sort of scripting/trigger events and so on.
That way we could make our own campaigns and such if they didn't want to dedicate so much effort to it.
They could also then add campaigns later on if they wanted.
I'd like to see the 3-dimensional aspect improved slightly both in control and map layout, and being able to have rotating turrets with defined tracking speeds and to either have projectile rounds modelled (so they can miss) or at the very least be able to set 'accuracy' ratings so you can have powerful heavy guns that are less useful against smaller, faster ships.