Who would win?
The dominion has the High Elves, with the best navy and mages in Tamriel. The best archers, the bosmer, and the Khajiits, skilled assassins and pickpockets able to perform skilled espionage. I say they would win. Quite easily infact.
The Nords have always been distrustful of outsiders, no doubt their pride would keep them from working easily with the two foreign races. And then the dunmer and Argonians have always had animosity towards each other due to slavery. And with none of them have a very advanced navy they could not easily reach the Aldmeri dominion.
So, who do you think would win and why?