I do think goblin lore will get fleshed out in the South Seas xpac, since its likely goblins will play a big part in it, considering it's their home territory.
Unfortunately, I can't see worgen lore being fleshed out for a long time, if ever. Blizzard has a habit of adding lots of new characters and then realising they don't have time to continue all their stories. It's a shame, considering how great the Gilneas/Silverpine quest arc was on both sides.
Speaking of Silverpine, Sylvanas is now off the deep end since War Crimes.
Ha, remember that, War Crimes? Remember how it looked like significant character development was going to continue in WoD? Ha. What has Sylavanas been doing this past year, being crazy in Undercity? I mean Jesus, that was one story they really should've continued, but Blizz being Blizz, they didn't. I also think it's still a bit early for her madness story to start (we all knew it was going to come at some stage) considering we just finished killing off the former warchief of the Horde.
Oh woops, did I say us? I meant to say Green Jesus. Silly me. I hope they just rope in King Mary Sue to be a background character in future expansions, since I doubt Metzen would let him be killed off, at least not without going the Broxigar way. Get Richard A. Knaak on the phone, we need another fanfiction main character since his last one was killed off!