My money is on Astora or Carim as the setting. If this is going to be a sequel, then surely it should deal with the Dark Lord's rise to be the ruler of the kingdoms of men. I'm hoping we will get to see a number of places which are referenced in Dark Souls though. Carim could be interesting, we never did encounter the goddess Velka, and Carim is a dark place ruled by Earl Arstor, who we know makes purging stones and resistance rings out of people. It's also Lautrec's homeland, and we all love Lautrec so very much. We also don't know much about the goddess Fina.
I'm really hoping they will expand the lore and give us what we want: to visit all these places that we have read so much about.
Then again, perhaps this sequel will deal with the transition from the Age of Dark to the Age of...whatever comes next. Perhaps the Dark Lord now occupies a similar position to that of Lord Gwyn in DkS, and much time has passed since Gwyn was defeated.
It would be nice to see several locations though, Astora, Carim, Catarina, The Great Swamp (you just KNOW there's gonna be a swamp...), the mysterious 'far East' etc etc. All of these places are far too interesting to leave them all out of DkS2.
So, what do you all think? And what do you HOPE?