Yep I can list most of them
1. Ra'den Quote: "Wait! I am... I am not your enemy. You are powerful, more powerful than he was, even... perhaps you are right. Perhaps there is still hope.
But there is a yawning chasm of darkness beneath you mortals, vast, endless, and all consuming. I do not believe that you can correct this doomed course.
But you have earned the right to try. Farewell."
2. The Blank Scroll: "Stormwind fell. The orcs reigned supreme. For a time.
The Dark Portal, left unguarded, was reclaimed by the Burning Legion.
Horrors rose from the sea and found no champions left to stop them.
Azeroth's mountains burned and melted. Its oceans boiled until nothing remained. And all was dark."
(Don't say it could be the legion as well, because after 5.4 the portal is still guarded.)
3. Ozumat: Fiend of the Dark Below as well as the stuff in Vas'hir
4. Erudax, the Duke of Below, who is a Faceless General, and if you know lore, they work for the Old Gods, specifically N'Zoth
5. N'zoth's Constant mentioning in Cata, and we know he's still out there.
6. The Naga and Azshara are still out there, and we know Azshara made a pact with an Old God so that her loyal people would survive and turn into naga.
7. Vashj'ir, that giant whatever the hell its name is thing is being drained for something huge underneath it.
8.
http://www.mmoculture.com/wp-content...013-poster.jpg | There's a lot of water in that poster, I wonder why. Thrall being a shaman is not the answer btw. I'll save you the post.
9. Yogg Puzzle Box
10. Could perfectly tie in the Legion expansion after it, with Azshara as last boss trying to use the remains of the Well of Eternity to bring the Burning Legion back. (This is obviously not a hint, just would make sense.)
11. There's more I can't think of right now, but this is more than enough hints at TDB being real
Better get some sauce to choke down that hat