The Nords that remain in the Legion, since many hold their oaths scared. The ones who believe their word means something and not easily broken will be without homes since the Legion which has been in Skyrim for hundreds of years won't be able to return since the Stormcloaks have taken power. Those who do leave weaken the Imperial defenses.
The Empire is all about protecting Cyrodiil? The Empire is Skyrim, it is High Rock. Cyrodiil is the seat of the Empire but it isn't all of the Empire. Cyrodiil was the front lines of a war, Skyrim was untouched. Hammerfell while it was a part of the Empire were also front lines in the Great War, the Legion was there fighting also. Cyrodiil is connected by two Aldmeri Dominion provinces. Where would you place your army? In Cyrodiil where the fighting will be or in Skyrim where it was untouched completely. Skyrim is protected due to geography.
Actually the issues with the Dark Elves isn't lack of housing it is actually their treatment. They're treated like lesser beings. Their living area was renamed the Gray Quarter as an insult. It was the Snow Quarter until I'm guessing when Ulfric gained power it was renamed officially as the Gray Quarter. That is like changing a city suburb to something insulting to a certain group who lives there. Though tell me in what way is Skyrim threatened? Considering the Empire has been sending what they can to assist in Skyrim, they sent Tullius, several Legates to aid Rikke and help the Auxiliary garrisons to combat this uprising. Then you have this;
"Because the Dominion is a sleeping beast that Skyrim cannot slay alone. Because many Nords are part of the Imperial army even now. Because the food and resources we get from the Empire are important to our people."
Oh poor Skyrim not getting cared about? The rebellion happened nearly thirty years after the WGC, if it happened earlier then yeah sure the Empire would probably be able to deal with it. Except they're spread thin, the Empire's focus is on the Aldmeri Dominion and the next Great War. The Stormcloak rebellion came out of the blue, no one was expecting the killing of the High King. Cyrodiil sends what reinforcements it can, but the focus is the next Great War. Ulfric's capture was supposed to be easy, except the Thalmor were helping him. Hadvar mentions that when ever they were about to capture Ulfric somehow he knew ahead of plan and managed to elude capture until Tullius was sent to deal with it.
We lost our capital. Holly shiiiiiiiiiiiii* lets sign every singe paper that thalmor send our way.
Reject our divine. Sure thing
Let us hunt your people like animals.
Sure thing, where do I sign.
We will roam freely trough your teritory.
Of course, just give me a quill.
Your secret police/bodyguars, they have to go.
Of course they do, I never liked them in the first place.
That... that pesky bandit filled province of hammerfell; it has to go, it looks bad.
I know man, I know, let me sign that.
Do I get to keep my throne and my shiny city?
Yeah you do, for as long as it suits thalmor interests.
Gray quarter, black quarter, white quarter, blue quarter, who cares?
What if they just said NO when red mountain erupted and sent them back to Morrowind? They wouldnt have that problem you know.
And dark elves arent angels either. Go to their shop its owner is a fence. Go to their pub they greet you like you are a piece of ...
You see them whining about their treatment yet they treat argonians like trash and even starve them to punish them.
Yeah, famous, infamous great war that only can be won by the incometent empire that wasnt prepared and lost the first one. 80 years of Thalmor preparations and not a single f was given those decades.
(as for garisoning cyrodil, if I was the empreror I would garison most troops in high rock and launch a counter-strike on high elf homeland the moment they declare war. But I aint.)