Alkenstar/Mana wastes for sure!
More Cities, Lost Cities, and Darklands locations!
Book of new Artifacts specific to Golarion.
Sourcebooks for Numeria, The Worldwound, The Sodden Lands, and Geb.
More fiction!
A book about Golarion's minor cults, dead gods, etc. which contains lots of pregenerated stat-block humanoid enemies and a few new summonable monsters.
A book detailing one or more other planets in the solar system, perhaps in conjunction with a module or adventure path involving the witchwyrds and inspired by the old "Expedition to the barrier peaks" adventure. Could have tie-in sourcebook for whatever passes as sci-fi in Pathfinder.
Perhaps psionics if done well. But I cast my vote against any of the nonsense that is epic. Oh, and I'd be extremely happy to NOT see a pathfinder 1.5 or line of "essentials" books in 2012 (or actually ever).
I'm sure whatever Paizo does for 2012 will inspire many great gaming sessions at my table.
Also, a comment - Paizo products are generally great. (I hope that any rules issues/ errata are addressed - I chose Pathfinder over <<another similar game>> in part because there were less rules problems, tighter editing, and beautiful print quality. would like to see this continue, no matter what products Paizo offers in 2012.