Again, without a Tribunal or proper home of their own, the Empire is basically the only place left for the dunmer, since they are the most tolerant of different cultures and races, even if it's not all that tolerant. Of course, the Empire hardly has the resources to go around oppressing people that aren't an existential threat to them at the moment.
Not so fast.
First of all, even with the Tribunal gone, Dunmer still have their basic Velothi cultures of ancestral/Daedra worship with them. The fact they built shrines of Azura and Boethiah in eastren Skyrim pretty much confirms they are still a vital culture, even if more nomadic now (one of the Dunmer in the game will tell you something like: "We are all Ashlanders now."). Second, the relations betwen Dunmer and Nords seem in fact to be far more cordial than the surface-level racism of Windhelm seems to suggest. In Riften Dunmer seem to accomodate quite well, in Winterhold, dark elf was an archimage of the College (and, before the collapse, it has been stated the city experienced a cultural renessaince due to the influx of Dunmer refugees from the east). And in the current situation, after the Great War, the Dunmer and the Nords in fact have a lot more in common than is divding them. Dunmer traditionaly hate the Empire, and now the Nords have every reason to dislike it as well. The Dunmer trace their history from their initial conflicts and split with Altmer and other elves, and the Nords also see their history begining with the wars against the elves, so they can sort of agree on that issue as well. Third and most important, a lot of the Dunmer culture and Tribunal mythology is based on the myth of mortals-becoming gods, which is, in theory, very much alike the Nordic concept of Talos (not to mention that the ultimate source of the divinity of both the Tribunal and the Talos is the same - Lorkhan!). So, Dunmer and Nords agree on three fairly important points: 1) dislike of the Empire (in its current form, at least); 2) dislike of Altmer/Thalmor; 3) Lorkhanic/Pandomaic mythical outlook where the mortal world is a trial, rather than a prison. All in all, I think therefore Dunmer would be far more likely to align with the Nords/Stormcloaks against the Empire and Dominion, than even staying neutral in the conflict, let alone going against the Nords.