I'm not saying the option is bad, just that you have to look at the opportunity cost.

And I'm sure they'll do something with Crystalsong eventually, probably turn it into more max-level content, but my point is that I think they put it off because they realized they already had too much midgame content, or at least that it wasn't necessary to add more.

I have been doing some reading, and I'd like to get back to the topic of Yogg-Saron and his possible involvment in Ulduar for a second.

First off, let's have a look at where profound traces of his involvment can be found:

1) Howling Fjord
Loken:
Come, minions! Your master calls!
The work of your brothers in the Storm Peaks has reached a frenzied pace. Soon, Father will be freed.
Your brothers to the north have subjugated the stone behemoths and set them on the path to Ulduar. Soon, the remaining defenses of the Pantheon will be neutralized.
The three fissures opened by the mortals of this region must be silenced. The earth hears and sees what we do and will continue to interfere with our efforts if the way is not closed.
Bury this place, your master demands it!

Plus, the whispers in Whisper Gulch which are obviously Yogg-Sarons.
Notice that Loken is talking about freeing something here, in this case "Father". Keep that in mind.

2) Grizzly Hills
Obviously a lot of traces here, all of the Grizzlemaw-Quests basically coming to the solution that the old world tree was corrupted by Yogg-Saron, with Ursoc confirming this.

3) Icecrown
Firstly, there's the Saronite mines in Ymirheim. You hear whispers of the old god, plus the slaves try to reach "him" by jumping off ledges. Also, Darkspeaker R'khem, another faceless one, who disappers after being freed by us.
Secondly, Naz'anak and the Faceless Lurkers, who mention Yogg-Saron upon being engaged.

4) Dragonblight
Ahn'Kahet: Obviously lots of traces here, with Herald Volazj and the other Faceless ones at the end of the instance. There are a few quests that refer to the Nerubians "digging to deep" and "exposing a tendril of the old god's will" underneath Azjol'Nerub.

Also in Dragonblight there's this one quest that confirms that the Scourge and Yogg-Saron aren't working together, with the Scourge being afraid of him and all.

5) Storm Peaks
Now, let's get to the interesting part. What kind of traces are there in Storm Peaks? We have:

• Thorim being enslaved by a bunch of tentacles - Loken mentions luring Thorim to his temple (which is closer to Ulduar than the Temple of Storms) in order to "fight closer to his masters power".
• Halls Of Stone: No real traces of him here, apart from a whole lot of lore during the Tribunal of Ages about the Titans and the Old Gods, and how the Old Gods were locked up beneath Azeroth.
• Halls of Lightning: Loken mentions Yogg-Saron and how he is going to free him, in essence confirming that "Father" is indeed Yogg-Saron.

Now, let's see where that leaves us: We can confirm Yogg-Saron has a lot of power near Ulduar, and this could leave us with the conclusion that that's where Yogg'Saron will be. The only thing that bugs me about this is that a titan temple isn't exactly where one would expect to find an Old God, especially not "the beast with the thousand maws". But remember: This isn't C'thun, and this is not AQ. Yogg-Saron has not been waging full-out war like the Silithids, he's only been "corrupting". We don't know whether he has armies or just a few followers who where imprisoned whith him beneath Azeroth. And now the most important question of all: If the titans were looking to keep Yogg-Saron safely locked up, why not build a temple full of their servants right ontop of his prison? True, that's not what they did with C'thun, but C'thun's story is different. C'thun fell in battle with the Titans and ended up in the desert of Silithus, he was hardly imprisoned there.

Keeping all this in mind, I think it is pretty safe to say that Yogg-Saron will be the final boss of the Ulduar raid, with us taking a big old Titan elevator down into his lair...or something like that. Ulduar will have to have an instantly recognizable endboss, and "corrupted thorim" just doesn't quite seal the deal. Seeing how all the lore builds up in Storm Peaks and expecially the Ulduar dungeons, anything short of facing Yogg-Saron in the raid just seems like a real let-down and wouldn't make any sense.

Yeah, I agree that Thorim wouldn't be a good raid boss. I mean, Loken was more hyped up than him.

Maybe it'll turn out to be Al-Akir. Has there been any explanation of why air elementals are working with the iron dwarves? It's still probably too random, but it's worth throwing out there.

Right, time for some ulduar speculation.

It's really hard to get an idea of the layout of ulduar from the exploration movies, but it seems that after you enter you reach a central room with big stairs, From there you can go left or right, both leading to a boss room at the end. Up the stairs you cross an invisible bridge to the main hall, from which you have four wings.

- an ice wing, containing at least one boss and probably more (several paths which are not explored in the movie)
- a jungle wing, which seems to just have one boss
- an arena wing, probably containing two bosses (one in the arena itself, one on the platform overlooking it)
- a wing which seems mostly unfinished now, naming it tree wing for now because of the big tree that is the only recognisable thing in there. There is also a big church like room shown which probably belongs in this wing.

Now combine those wings with this quest: Fate of the Titans

The jungle wing resembles sholazar basin so much Freya fits perfectly in there. The only alternative boss in that wing I can think of is a proto-dragon, if such a thing even exists. If Freya is in the jungle wing, it is very likely the other watchers are there as well. Hodir in the ice wing (the quest mentions his temple no longer having "cold weather patterns", maybe he causes them in ulduar now) and Tyr and Mimir could easily fit the remaining two wings.

To catch back on the final boss speculation, there doesn't seem to be an obvious room for a final boss. Probably some hole will form somewhere you can jump in order to go to Yogg-Sargon, but it would be really cool if he actually just surfaced in the main hall, destroying most of ulduar with it.

My bet on Thorim is that he will be similar to Akama. We face him early in the instance (perhaps in the first room with the stairs?), redeem him and then he will tell us to go redeem/kill the other watchers, followed by him (or them all) helping out on Yogg-Sargon himself.