Spoilers dude! Spoilers!
Ok, this here is basically a block of text to prevent people looking at this blog on a mobile site from seeing the massive spoilers coming in. So spoilers, dude! Spoilers. These are some very juicy spoilers, and they're at risk of getting all spoiled. So spoilers.
Right, we good?
We had a pretty good idea that the initial battle at the Broken Shore was going to be a Grade A snafu. And now we're starting to get details. What details are those?
Well, both the Alliance and the Horde are getting a change in leadership, though at least in the Horde's case it might only be temporary.
Let's start with them. After the Broken Shore, Vol'jin will be MIA. Presumably leading the Horde forces to counter the Legion, he disappears, and someone has got to take his place. The good news is that there's a seasoned veteran who is an effective military leader and is relentless in combat. The bad news is... well, the senior leader within the Horde, who has been a part of it since vanilla... is Sylvanas Windrunner.
That's right, Warchief Sylvanas Windrunner.
Granted, Vol'jin probably isn't dead - narratively they'd just kill him if that were the case. Still, it's gotta suck for the guy to basically become Warchief, sit the next expansion out since it all takes place on another world, and then to start his first potential expansion as a powerful and strong leader and... get taken out. Still, I strongly suspect that much of the Horde story is going to involve getting Vol'jin back. Still, making Sylvanas Warchief is a bit of a provocative move on the part of the Horde. Still, with all the crap that's going down, it's not like they have much of a choice.
The Alliance, however, has a more explicit tragedy. King Varian Wrynn will die during the battle. We don't know if it's going to be in a last stand against the demons or if there will be some kind of Horde treachery (though can it please be the former? If for no other reason that it's time to see some Alliance treachery for a change?)
That means young Anduin, who did serve as King briefly while Varian was missing, will now in fact be the true king of Stormwind. What does that mean for the Alliance? For Azeroth?
Velen did have a vision of Anduin leading the Army of the Light in battle against the Burning Legion, and if his father's dead, he's in a position to have the full might of Stormwind and potentially the Alliance behind him. Anduin has also spent much of his life trying to patch up relations with the Horde. While the Horde has almost always been the aggressor in their conflicts, if the Horde wants to make peace with the Alliance, Anduin would be a great leader for them to approach.
That said, we don't know if the rest of the Alliance will so easily fall in line behind Anduin, who at this point is only about twenty. Anduin has it in him to be a good leader, but he doesn't have the ferocity that allowed Varian to really establish himself as the High King. Anduin will have to convince and cajole people into following him. Velen's likely to do so without hesitation, and the Dwarves and Gnomes are such close, old allies of the humans that it shouldn't be too hard for them to fall in line. Malfurion and Tyrande already made the leap to allow a guy in his 40s to be their leader, so having a guy in his 20s isn't much of a compromise, given that the Night Elf leadership was already about ten thousand years older than the old king. However, I think the real potential threat to Anduin's control of the Alliance is Genn Greymane. Genn has been a king for several decades - he's an old man with lots of experience, but the vigor of a Worgen. Genn was the one who pulled his country out of the Alliance in the first place, largely because of what he saw as being too soft on the Horde (that being "not genocide.") Not only that, but Genn's (mostly) human, and he might feel that that gives him a privileged position within the Alliance, given that it was originally a human organization. As the oldest king of a human kingdom, he might feel that the Alliance should be his to command by rights.
The interesting thing is that we know that Sylvanas and Genn will both be on the Broken Isles. If Sylvanas has taken the reins of the Horde and Genn is vying to do so for the Alliance, we might be seeing the two of them clash against each other and try to drag the entirety of their respective factions into the conflict. Of all the conflicts of the "Fourth War" that ended at the Siege of Orgrimmar, the matter of Gilneas was left frustratingly unsettled.
So far there's no word on Thrall. Tirion Fordring might actually survive, as there seem to be quests where you interact with him after getting the Ashbringer. Still, it looks like, after the rather unqualified success of the Draenor campaign, we're in for a serious rough ride that is going to cost Azeroth some of its greatest heroes.
Whoa, not only that, but check these out:
There are NPCs that have been found in the files that should raise a few eyebrows.
First, there's an Undead Grom Hellscream (presumably Grom-A, given that they said that alt-universe NPCs probably won't be making an appearance, at least not in 7.0.) There's also humanoid Llane Wrynn, Varian's dad who was killed by Garona, which could possibly suggest some sort of flashback for the Assassination Daggers quest, though that's totally speculation on my part.
There's also Magni Bronzebeard, Lord of Ironforge. Thanks to a screenshot way back at Gamescom, a lot of people were speculating that Magni would get de-crystalized, as there was a variant appearance for the Ashbringer that said he had "forged it anew." (Magni was actually the one who forged the sword in the first place.)
Finally, probably the one I'm most excited for: Calia Menethil. That's right, Calia Menethil, also known as Arthas' little sister and the rightful Queen of Lordaeron, assuming she's still alive. Now, this could totally be a red herring. For example, the Swords of the Fallen Prince (Frost DK swords) were made from the shards of Frostmourne, and there's a good chance that Arthas' sister's soul was trapped away in them just like his father's. Still, I've always thought it would be amazing if Calia were either still alive or had become one of the Forsaken, hiding her identity lest she be taken out by Sylvanas as a rival. If Sylvanas winds up leaving the Forsaken as some have speculated, having an Undead Human who is also the rightful monarch of Lordaeron would be an awesome replacement, and really complicate any Alliance claims that the Forsaken don't have a right to those lands.
Another thing to keep in mind is that stuff like this, especially datamined stuff, can often lead you astray. In the beta for Cataclysm, people found sound files for an Alliance naval battle in Twilight Highlands that talked about the betrayal of Archbishop Benedictus, but that battle never happened (at least not on-screen for the Alliance) and Benedictus would not be revealed to be Twilight's Hammer until the Hour of Twilight dungeon. Likewise, Grand Magister Rommath was implicated in a similar quest as a member of TH. During Mists of Pandaria, people found datamined quests and dialogue talking about how Garrosh killed Anduin.
So everything we see here, remember that even major story stuff can change in development.