Honestly, I hope we get Xal’atath as a final raid boss of Warthin.
She doesn’t need to be dead by the end of the expansion, but it would be cool if she will be the final raid boss of Warthin but somehow ‘wins’ and that would bring us to 12am because she is the HARBINGER.
Oh goody, another, “not today” scream and boss escapes fight.
Can you list more 3 other final raid bosses of other expansions that manage to win and escape in the history of WoW?
It’s very likely that she would survive to show back up in a later raid. Blizz would prob pull a Iridikron, and make her a boss in a mega-dungeon to show up in a raid as the penultimate boss of said raid
Sylvanas, Ragnaros, I’m blanking on the name but that Naga/Night Elf chick that starts with an ‘A.’
No. Its, “enough”
/stun
Blizzard narrative employee: this. This is good. 
I hope she isn’t a boss and that she lasts at least into midnight. It would be a waste otherwise, even her just being a boss before midnight - she needs to be demonstrate that she’s one step ahead to actually pull off the story of midnight.
Cue goofy cutscene where they either escape or get killed by Thrall
Funny enough, I think another choice for the final boss is that crystal(?) in Hallowfall. The Arathi do seem to extend their turf into Azj-Kahet and even the unrelated Kobold’s invasion against the Machine Speakers would fit this enemy’s arsenal. Just my two bolts. 
I don’t think that’s the plan no, most likely it’ll be either she or Iridikron survive till Last Titan but the likely case is she’ll betray iridikron at one point. She may even cause whatever bad events happen in Midnight but I can’t imagine she’d die immediately like Razageth did
The first raid does worry me.
Garrosh, Illidan, Ashzara, Kil’jaden…
Xal might play a part but i doubt is the last boss of TWW
My prediction for the 3 end bosses is…
WW: xal
Mid: Azshara
TLT: Iri, amanthul, a void lord, or azeroth.
The final boss of warthin is a parotidectomy.
In World of Warcraft: The War Within (TWW), Xal’atath will be the boss of the first raid, where she will be defeated and sealed once again inside a small item where she can do no more harm. However, the events of the initial raid will lead to the awakening of the Naaru embedded in the earth, who will then be the boss of the second raid, where you have to defeat him to prevent his scouring Azeroth as a means of wiping out what he perceives as the Old God threat.
I hope N’Zoth comes back.
Many times the first raid has nothing to do with who the big bad will be in the last.
Iridikon seems like the perfect final boss for TWW. He’s an Earth Elemental dragon who’s associated with the Void. And where are we going in TWW? Deep into the earth to fight the void.
Neither of those are final raid bosses of an expansion. Ragnaros didn;t win anything at the end at all.