Preposterous to think the whole Dalran will turn Alliance just with a change of leadership. To Dalaran Jaina is, first and foremost, one of the greatest surviving mages and an apprentice of the great Antonidas himself. With the Six having both Alliance-supportive, Horde-supportive and Neutral-supportive members Dalaran is to stay as a centre for the mages of the whole world - an Archmage hardly dictates the policies of the state at their whim without the agreement of the Six. And with Aetas staying on the council and Rhonin, apparently, leaving (thus rendering Vereesa's opposition effectively powerless) I see little ground for the republic to suddenly agree with Jaina to help her revenge and throw their lot with the Alliance.

Now, maybe Dalaran will help her with the "Kill Garrosh" plot, but then, I don't think they will be the only ones to do that. How about a "Taking Theramore from Daelin" situation with roles reversed: Thrall and Vol'jin providing Alliance and Dalaran forces cover help in exchange for getting Garrosh out of the city and leaving civilians in peace? It worked for Jaina, at the time.

EDIT: Remember that night elf supremacist Fandral Staghelm? Yeah, the one who hated the Horde and was giving quests to "wipe them out, all of them". Before Furion's recent return, he was also the leader of the Cenarion Circle, and, being in character, objected the idea of the tauren in the circle. And yet tauren druids became a part of it and still are in the circle to this day. Because quasi-scientific/sacred organizations like a community of mages or druid does not operate on the whims of one person (and when it does, it ends in total disaster - look at poor man Gul'dan's whole warlock pandemonium!). A leader has power, but so do the councils of other leaders. Dalaran is a republic, after all.

Logically I think, the Sunreavers would be kicked out of Dalaran and it will join the Alliance. I mean, look at the hints! The Sunreaver spy comes to mind. The Horde might still go to Dalaran in Northrend, which will remain in the Wrath timeline, but, on the other hand, in some other location, Dalaran can be an Alliance city. Also, the most of the local populace of Dalaran favour the Alliance over the Horde, as it is primarily a human city, with a considerable number of high elves, who hate the Horde.

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