I been real bored between raiding so I thought about possible ideas for new content. Now I don't have a huge knowledge base for lorecraft, but I don't think I'm that far off from possibilities. They are listed by the possible main enemy, like Naxx's Undead or Ulduar's "Metal Monstrosities."
Raids:
Trolls - There is an enormous building NE of Gundrak, perfectly made for the look of a raid dungeon. Obviously it would be kicking the crap out of trolls... again.
Vrykul - We have explored the bottom level (UK) and the top level (UP), but there is the possibility for a Vrykul based raid using an underground complex beneath UK.
Spiders - Plenty of "unexplored" cave space in the Pit of Narjun in Dragonblight. The spider's need to have a "new" kingdom to replace their "old" kingdom, and I doubt Azol Nerub will cut it.
Dragons - Obviously several more doors yet to be open in Wyrmrest Temple.
Grim Batol - I'm not sure who would be the main enemy as I'm not fully read up on the lore of this event. But it could be a CoT dungeon to experience the past, or a current dungeon to quell another Old God who has taken residence in Grim Batol.
Icecrown Citadel - Nuff said
New Expansion
World of Warcraft - Maelstrom
A continent rises from the Maelstrom between the other continents. Ruled by Naga and whatever goes along with the Maelstrom in the lore.
This would open a new continent without changing the map. IMO the spiral at the center of the map is semi-ominous enough.
We gave Prince Kael'Thas TK after we beat him up in MagT, and KT a reformed Naxx, so what about Lady Vassj making a comeback in the new expansion.
This would also place a new expansion solidly into current lorecraft as the need for new lore is becoming apparent once we kill the Lich King.
Also, two realm/faction wide events like AQ:
Alliance:
Gnomes take back Gnomergon, but accidentally blow it all to hell. Requireing the aid of all the Alliance to rebuild it.
Horde:
Darkspear Trolls take back the islands in southern Durotar (cant remember their names) and the Horde helps them build their own city.
I realize that they are alot like AQ... but it would stop all the Gnome/Troll City QQ from lore geeks
These are just my thoughts and what I've come up with over the past few days, feel free to post other ideas or CONSTRUCTIVE criticism. I could also use help clarifying any lore mistakes or ambiguities I may have made, or lore additions to my ideas.