I wonder who is the leader of the Thalmor/Aldmeri Dominion? I wonder if s/he (or it?) would be revealed in a future game which we'll get a chance to kill him/her or it? (of course I hope a future game or DLC would involve fighting the Thalmor)?

We just don't know.

Though, if the historical Thalmor are anything to go by, there is no single leader and they come to decisions through consensus.

They seem like a very bureaucratic sort.

The red tape ! Imagine the Red Tape !!

I would assume the most inbred, pointy-eared, golden-skinned "pure" Elf available.

Though it could just as well be someone seriously overcompensating for their own lack of elfiness.

Yeah, this seems like the most likely thing.

The current High King maybe? It's not without suspect that they'd try to replace the throne with someone they can trust.

Well, the Thalmor is an old Altmeri family (family used in a similar way to a Great House of Morrowind, political party might be a better term though), so the snarky answer is "the leader of the Aldmeri Dominion is the Thalmor." I'd imagine Falinesti is also involved in the decision-making though, since their relationship is ostensibly cooperative.

I imagine it's rather like the shadowy figures at the beginning of the original Deus Ex: a silhouetted and clearly evil council of snooty mysterious types, mumbling cryptic jargon and sideways-speak to each other in front of a bunch of televisions showcasing their plots all over the world.

I like to think that the Thalmor are run by a council of, essentially, Theocratic Mages with huge burs up their collective asses.
They are run by a council, which in turn is run by another council, which in turn.... I think you get my point.
Right up until you find exactly this
when you accidentally reach the top of the food chain.

Does anyone know what happened to queen Morgiah? I suppose that the Thalmor get rid of her.

Most likely. Really, Barenziah was a more series-centric character (as in, one of those characters who is really important to the series in general), and the only remnants we have of her are her destroyed crown and her bastard granddaughter.

Decisions are not made in Alinor, they are reached. The Dominion is a "a society so harmonious, so fine-tuned, that's it would be an awkward and terrifying experience for any stranger, who could never be be made to feel like a welcome visitor, but would be like a foreign body in the machinery."

Shor in disguise. He's just baiting them around so that he can crush all the silly elves once and for all.

i thought the thalmor were the leaders of the aldmeri dominion?

I think the Thalmor are the "leaders" of the Aldmeri Dominion in the way that the Democratic Party are currently the "leaders" of the US, or the Republican part are the "leaders" of the... whatever thing they have control of. blah, I'm too tired to be thinking.
you get my drift, yah?
They're more like a broad group or movement whose ideology and policies controls the Altmer government, and whose prominent members are important in Altmer politics.

Yeah, the Thalmor run the Dominion in the same sense that El Presidente's party runs Tropico. But we still don't know who El Presidente is in this case.

I'll tell you who the leader isn't, a Khajiit prisoner who joined on killing rats and gathering eggs who eventually rose through the ranks to kill the Arch Magister.

Because they leave that for the gobs.

No, our Khajiit prisoner joined by delivering a mysterious wraithcoded package to an old Mirror-Logician living in a secluded forest cottage...

Please. Our Khajiit prisoner was never a Khajiit at all, but rather an Altmer assuming the guise of a Khajiit (by breaking through Y'ffre's laws as a Necromancer breaks through Arkay's) in order to better infiltrate the Pelitine society and replace the Mane with the soul of Qroyo who perished in the fall of the Crystal Tower (it's not like you can tell who's under all those braids anyway). Having completed this prestigious task, he seeks to return to the Isle, only to be waylaid by one of the numerous space-time anomalies that litter the southern waters due to Numidium's continuing conquest (thanks, Tiber!). He washed up ashore in some random cave, and the rest is history.

I can see the Thalmor being led by some sort of parliament of important Altmer throughout time who meet via dreamsleeve and relay their decisions through a Mouth type person who is really just a specifically engineered shell-body. This act tends to burn the body out, hence there's a whole bunch of them, and any Altmer worth his salt would be greateful to serve as one.

But, in terms of what we may find it game, it's likely to be some sort of Hitler person.

Actually, our Khajiit prisoner is the last surviving Ayleid, as the last true heir of the House of Camoran, which had been inexplicably tied to the House of Thalmor during the Dragon Break when a princess gave birth to her own father, who was a Dremora conceived during the Oblivion Crisis by Sheogorath after he had become a Khajiit at the end of the 3'rd era in the future, thus breaking his own possipoint forcing him to do a crap load of [SKOOMANIT]. This impossible Khajiit-Bosmer-Dremora heir to the House of Camoran, thrice-blessed by Meridia (except on Tirdas for such a thing is blasphemous) in order to combat the rare case of congenital Padhemophilia had inexplicably been born as the first incarnate of St. Nectar of the Ayleid kingdom of Kantthinka-Noth-Ingbettar by virtue of his odd birth meeting the requirements of St. Nectar's odd prophecy which was made right before his entire kingdom collectively reached Zero-Sum rather than suffer through Pelinal's rarely mentioned Math Crusade. This last Ayleid, known by Thalmor Aurbimancers as the Nectarine would go through life plagued by his obsession with Khajiiti pormography, later taking his obsession to the next level, producing a Khajiit child owing to his impossible blood. That child, long known to the Grand Floaters of Artaeum would eventually be imprisoned because of claim to the throne and subsequently freed when the dreaded left kneecap of Numidium sprung from its chrysalis shell and vibrated all the Alinor jailers a song of infinite sleep originally penned by the Dwemer echosmith Barrum Manolthar.

After escaping prison, the Khajiit killed an awful lot of rats, most of which were invisible which could only be killed with similarly invisible weapons. It was here that the Khajiit not only displayed his skill with the invisible crossbow and his invisible spear, but also earned the undying admiration of Irthena Drelas, who representing the insanity of the Godhead both loved and hated rats, especially the invisible ones. Little did the Khajiit know that she was in fact a rat, and he was really the invisible one. [End of fragment]

No, no, no, you're all wrong. It was Vivec.

Maybe it's that mysterious elf making snide comments on the first edition of the Pocket Guide.

This. So much this. I would give my right arm to know what YR is up to these days.

"After realizing the Dominion wasn't taking him back, YR became a miserable alcoholic. This was worsened after the Dominion was destroyed. After 40 long years of living in this condition, YR found the Alessian Nine Divines religion. Finding it more peaceful than the cruel Eight from Summerset (for that religion would teach him he wasn't perfect), YR eventually overcame his rampant alcoholism."

"He died five years later of liver complications due to his bout with alcoholism."