I'm personally hoping for Deathwing in the next patch. Not because I want the final raid of the expansion to arive already, actually its quite the opposite. I personally don't want Deathwing to be the final boss of the xpac, I would rather fight DW in 4.3 and have the War of the Ancients in 4.4 or even 4.5 and have it be revealed that there were greater powers pulling DWs strings behind the scenes, steering him in the direction he's taken. Personally I think it would not only make for a more interesting story for the current xpac, but also lead to a better transition to the next one by setting us up with the next big bad a little early.

I also have a theory that Sylvannas could come into play in the story soon. What she's been doing since the fall of Arthas is probably the most interesting point of Catas story to me and it has been barely touched thus far. I doubt they'd give us the build up they did in gilneas and silverpine with no plans at all to expand on the story. The likeliness of her becoming a raid boss in this xpac is probably unlikely but I would rather enjoy SOME type of story to come about that centers around what she's been doing with the plague and the Valks.