Wait, we have to wait... until...
APRIL 2013?

[censored].
Spoiler Did Sam die or did the white-walkers leave him alone?
Also, not as many main characters died in S2.
And while I haven't even read the books, this is just a theory of mine:
At the end of the series, it's going to come down to Denaerys' dragons against the White Walkers. She might die or have a change of heart, but the dragons are going to pretty much be the key to stopping them I think. Maybe they will come under the control of Bran and (his brother). I think Rob will die off. He will besiege King's Landing, maybe control it shortly, or something drastic will happen and his plans will come crushing down on his head (like what happened with Eddard). Arya may reunite with her brothers. I think Stannis will invade King's Landing again, he will be successful, if only for a short time. Tyrion will probably be important all the way up until the end, but I see him dying, maybe in an act of honor or bravery. Jon will unite the wildlings under him, or get them to work with everyone south of the wall to defeat the White Walkers. The Greyjoys will probably die. They aren't very developed yet, so I can't really tell. Jamie will most likely be an antagonist throughout the series. Jamie, Tyrion and Cersei's dad (don't know his name) I think is going to die soon. Unless they start developing his character a lot, I don't think he'll last as Hand of the King.
This is just my speculations, really just rambling on about what I think will happen. Was a good season, looking forward to the next. Thinking about picking up the books.