I feel like this is impossible to determine without knowing how the events of Skyrim turn out.
You'll have a very different result if the Emperor is assassinated and the Stormcloaks win, than the opposite. Or even if Ulfric and the Emperor are both killed, but the Empire retains Skyrim. Or if the Emperor lives and the Legion is successful in Skyrim.
What does the Last Dragonborn do? That's equally important.
The political map is hinged upon Skyrim. High Rock, Hammerfall, Morrowind, and Cyrodiil are all affected by the events there. If Skyrim secedes, High Rock is stranded geographically from Cyrodiil. Hammerfall might form an alliance with Ulfric's Skyrim. High Rock might be less politically aligned to the Empire than we think and decide to have independence too. Morrowind is vulnerable at the moment. What would a Stormcloak victory mean for the Great Houses? Would Cyrodiil push for closer relations? How would Ulfric handle relations with Morrowind?
Does the Dominion want to eradicate the Empire? Why? If it crumbles beneath itself, isn't that their goal? Do they really want to conquer Tamriel? We haven't seen that behavior so far.
Too many unknowns.