(This post contains possible Cataclysm spoilers about Thrall. You probably already know them, but if you're really avoiding any Cata knowledge you might want to skip this one.)
Since writing the previous post, I've been doing some more thinking about what's left in store for Jaina. While Tam's suggestion of "stuff her in a bag" is hilarious (and fitting) I think all is not lost for poor Miss Proudmoore. While the Jaina-Lich King theory would have been great, I think a suitable ending may still be possible for her, while still tidying up the loose ends as previously discussed.
Recapping, the loose ends with Jaina are as follows:
• She is one of two human "leaders", a political position unique to them. This situation only exists because Blizzard needed a "face" for the humans when there was no Varian. Now that he's back, it's awkward and desperately in need of updating.
• She has always been the peacekeeper between Horde and Alliance. This role cannot exist in Cataclysm since the factions are pretty much at war, and the only reason her mediation was possible was because of her friendship to Thrall (who everyone knows will have stepped down.)
• Her primary motivations - representing the humans, representing the Kirin Tor/mages, and saving Arthas - are finished. Varian and Dalaran are back, so she no longer needs to shoulder those burdens, and Arthas is dead. She needs new goals and direction.
I think this leads quite nicely up to something only jokingly referenced to previously - the pairing of Thrall and Jaina.
First off, Jaina might be depressed (big surprise) about a few things at the end of Wrath. Arthas is dead, so of course she'll be mopey about that. But she'll probably also be quite disheartened when Thrall steps down, and not just because they're friends. She's isn't dumb - she'll recognize that Garrosh taking over as Warchief means peace between the Alliance and Horde will never happen. Maybe this will be too much and she'll withdraw from the political scene, then see what Thrall is doing and realize there are bigger things at stake than old hatreds. I wouldn't be surprised at all to see her step down as a "leader" of the humans and join Thrall in his new job.
Secondly, speaking of Thrall's new job, we know he is stepping down, presumably to take up the role of Guardian of Tirisfal. Who was Jaina's mentor, until recently? None other than former Guardian Aegwynn. If anyone would understand the responsibilities and duties of the Guardian, it would be Jaina. Plus, Jaina's knowledge of arcane magic and the history of the Guardians would likely be very useful, since the previous Guardians were all mages, not shamans. Also, some races (night elves...sigh) would probably be extremely reluctant to accept an orc as the new Guardian, even Thrall, the most peaceful, diplomatic orc ever. If Jaina, who's pretty much universally known and trusted, were alongside Thrall it would go a long way to smooth tensions and alleviate racial barriers.
And finally, Jaina and Thrall have been bizarrely close friends for how long? It's no secret that they are very close friends, and trust each other's opinions intensely. The only thing really keeping them from hooking up has been their faction responsibilities and the fact that Jaina was pining uselessly away for Arthas. If they're no longer Alliance and Horde, and with the specter of Arthas no longer weighing on Jaina's mind, it's only a matter of time before they become a couple.
And hundreds of fanfic writers will SQUEEEEE in simultaneous delight. ;)
Sentimentalism aside? This would actually be a GREAT idea. Two of the noblest, most selfless but also strongest people working together to save the world? Harnessing both the power of primal elements and arcane magic? And each with the knowledge and experience of being a powerful leader with great responsibilities? Yeah, that sounds pretty potent.
Not to mention that both still hold immense political sway and influence within their respective factions for when things invariably spin out of control, and they need to step in and say HEY, STOP FIGHTING GUYS. THERE'S KINDA MORE IMPORTANT THINGS GOING ON RIGHT NOW.
So yeah. Jaina, you'd be better as the new Lich King, but if you want to hook up with Thrall and help him grow into his new role as Guardian, and together spread peace and love throughout Azeroth, I guess that would be acceptable too.
AND SHE'LL FINALLY STOP CRYING AND BE HAPPY!!