We don't know the terms of the treaty with Hammerfell, and Talos was never big there to begin with. They objected to losing southern potions of the country which they ended up destroying in the process of driving the Dominion out. So again not necessarily a victory.
Cyrodiil was destroyed and yet the justiciars are free to operate there. That's better?
Yet when Ulfric takes power the Thalmor remain in Solitude.
Entirely a game mechanic. Same reason why the Penitus Oculatus remains in Dragonbridge and you get a bounty if the Stormcloak guards see you attack them- because they need to be there to be available for quests.
Ulfric managed to rally a sizable army behind him, if he had put that effort into rebuilding the Imperial legions then they may have been ready for war with the Dominion. But no instead he builds the army names them after himself in a grand show of megalomaniac and kills the High King without even talking to him about it. Anyone who doesn't kiss Ulfric's boot gets kicked he says he's all about freedom for Skyrim but he won't accept Balgruuf's neutrality. (Tullius does).
Have you been around for any of the 296,784 threads on this subject? I get tired of repeating myself. *reads off list* Ulfric did speak out about independence- at the moot. And the Stormcloaks were perjoratively called that name by their enemies and took it as a badge of honor, sort of like yankee doodle. Balgruuf is not neutral- he's imperial.
Ulfric's civil war only weakens the Empire and Skyrim, had he put forth his time and effort into rebuilding the Imperial Legions that were lost keeping the Dominion from ever reaching Skyrim in the Great War then maybe the Empire would be in a position to fight the Dominion on its terms.
Skyrim was keeping Thalmor out of Skyrim. It was Nord legions who saved Mede's ass after he lost the Imperial City, losing their own territory to the Forsworn because of it. I don't see the empire being able to invade, either, but that is all moot as long as the empire is permitting Thalmor to operate in Skyrim anyway. With friends like that...
This is all off topic.