If we're talking new weapons... I dunno... maybe a flail? Flails have always been awesome, but ever since seeing the Peter Jackson's version of the Witch-King, I keep thinking of mages wielding them, not warriors or rogues. Especially since mages have no choice of weapon right now.
If we're talking about stories... there's always a DLC that segues into the next game, so I expect something with Tevinter and/or Qunari, though I don't know if we'll actually visit the country. I imagine new DLC will be located in Orlais or Fereldan, and make themselves known with new Scouting missions and semi-open areas to explore.
What would I like to see? More Tevinter. Something that doesn't just say 'these are bad guys'. But who knows, maybe that'll be in the main game (that being said, Dorian is a single swallow, so right now there's hardly any trend that doesn't say Tevinter is the seat of all evil...) I'd also like to see new schematics, weapons, and new decor selections for Skyhold.
Casual outfit DLC and Qunari hair DLC would be nice but I'd prefer patching them in as opposed to forcing me to pay for them. If they mixed it with a face melter (i.e. Mirror of Transformation), I'd warm up to the idea more.
Excursions to Antiva, Rivain or Seheron would be nice, as would any Marcher territory other than Kirkwall (but I'd change my tune if they game me a good enough reason). New actual cities to explore would be a dream come true, but unlikely to happen....
Oh! And new, PC-only specs would be ridiculously awesome, especially if bundled with story content. Imagine Battlemage, rethought as a melee-range fighter, using a staff as a defensive weapon (held in two hands). A passive ability forces battlemages to fight close. Maybe even build guard... Ooh... ideas.
P.S. Also, ruins.