This is exactly why the empire was foolish to give up. The Thalmor only seemed to get as far as they did because of their general's strategies. He's captured in the battle of red ring leaving the thalmor army(whatever defense force is left in summerset) without a good general or leadership(And their main army completely destroyed), and they give up? Had they asked it of them, the nords would probably have been pretty happy to march down there and continue the battle for them. Seriously, Mede's not a very good politician. He's the son of a merc leader that happened to take advantage of a major crisis. When an actual war broke loose he had 4 nations on his side against 2.(Would've only been 1 if he had been proactive and tried to salvage the empire.) Mede let the empire crumble into what it is today.
Did I use one example of other races not having any issues? Nope. You seem to have completely ignored the dunmer of windhelm which are expecting special treatment. No other stormcloak city has that problem. Dark elves and argonians run shops in riften, the college of winterhold is run by elves. If you want all races determining the government then go back to cyrodiil which...oh wait it's completely run by men too...perhaps dagger...ah nope all men there too. Hamm...nope. Maybe there are some nord leaders in Morrowind? Ah it appears not. I'm sure the king of Alinor, Ingvar Wolf-scar will set the example for...oh...huh...
You say the nords betrayed the empire? The banning of talos was a pretty big betrayal to them.
Ulfric's a terrible leader, Balgruuf would be a better choice(And had it not been for Ulfric, I think he would've been on the stormcloak side).
The casualties for the EVERY SINGLE LEGION (aka almost the entire army of all the human races).. including the Nords of Skyrim.. was greater than 50%. Their homeland was devastated, entire towns razed, etc. They have no reinforcements. Morale is incredibly low.
The Thalmor's homelands are completely untouched - they have reinforcements ready. They can even build up even more reinforcements faster, and have much more supplies, due to a pristine homeland. They only lost the one army. They have plenty more. Ultimately, though while the terms of the treaty were really harsh, there was no way in hell that they would be able to invade the completely untouched, highly motivated defenders of the Thalmor lands, when most of them are already on the brink of death. There's nothing else they could have done, unless they just refused the treaty and died in round two.
The "Dunmer want special treatment" thing is crazy - because the race is a little be arrogant that means they deserve to live in slums, have no protection from the guards, be regularly assaultd and harassed by citizens, have merchants deliberately ignored by guards so they can be robbed by bandits, and be unwelcome in the rest of the city? Did you actually talk to the Dunmer? Most are melancholy and depressed, not arrogant snobs. Did you check the docks outside, where the argonians are only allowed to live in a shack and aren't allowed to enter the city or gain jobs within the city? Did you talk to the Nord war veteran who tried to talk to Ulfric about helping smooth some of the racial tensions, but was pretty much given the middle finger and ignored?
Everyoen acts as if the Legion is incompetent, yet the Legion had already won the war when the game started - the stormcloaks just got lucky and got a second chance. The only way the stormcloaks win is if a Dragonborn backs them - that doesn't make me very confident on their ability to take on the Thalmor, who has already BEATEN THE CRAP OUT OF SKYRIM'S ARMIES.. when skyrim had High Rock, Cyrodiil, and Hammerfall on their side too!
Hell, even the battle that finally kicked the Thalmor out of Cyrodiil was with Mede leading, and was a part of Mede's overall plan - people keep trying to portray as if he just was losing and the nords came in like superheroes and saved the day. The history books pretty clearly state he pulled out of the Imperial City when it would have been an inevitable defeat to save his forces, then gathered all his troops and attacked all at once.
One law temporarily banning a god under duress that will be repealed as soon as possible is no 'betrayal' compared to betraying the rest of humanity that's trying desperately to stay united in the face of a greater threat.
What do you think will happen to the Empire without Skyrim. You might say "good riddance" to them, because they were WEAK AND SHOULD HAVE FOUGHT TO THE DEATH LIKE MANLY VIKINGS, but that's an idiotic plan anyway. Ultimately, though, skyrim is only 1/4th of humanity, and by seceding, they're pretty much giving them the middle finger and leaving them to their fate. If four provinces together lose against the skyrim, provinces that are invaded one at a time will surely lose.