While I do believe that a second Great War with the Dominion is likely to happen (And I hope its one of the main points of the next game), we have to think. The Great War lasted four, to five-ish years, give or take any lingering resistances. While it was a stalemate, the Dominion forces in Cyrodill were annihilated, the Imperial City was sacked twice, and a few of the Dominion's generals were either killed or captured. With this in mind, and how the Empire is in Skyrim (And the Emperor possibly being dead in the next game, or pretty old), both sides were more than likely weakened. In my mind, with the fact there seems to be a fair number of Altmer and Bosmer who either outright, or secretly disagree with the Thalmor or the Dominion as whole, we have to wonder, how strong are they? For me, I think while they are rebuilding, they are still a while away from their strength pre-Great War. What do you guys think?
I would say that they aren't that powerful and that they will have to take more care of what is within their own borders before expanding (this is a general rule for all the countries in Tamriel).
What I mean by that is that there are indeed a lot of rumors about infighting and discontent within the dominion. You hear from Delphine (yes, she is a terrorist, not the most reliable source I'll admit), that the Thalmor are conducting purges amongst the Bosmer, which is never a good thing if you want a sustained control over the province, fear only gets you so far. On the other hand I don't think their control over Elsweyr will last a long time either. I mean, how long will it take for the smart race of the kahjits to discover that the Thalmor had nothing to do with the reappearance of the Moons?
The fact that the psyjics have renounced Thalmor rule is a good indicator of the weakness of their grasp on even Alinor. I don't think they will stand for much longer.
I think their warrior for warrior ratio is about the same as those fighting againt them. However, I also think they know / have something that might just change everything. Why else should they decide to start a war if they werent 100% (or as close to 100% as possible) to win? What this something they have, or know, or whatever is, I do not know... the heart of Lorkhan? Who knows?
To be honest I'm not sure if the ethnic cleansing is a new feature of Altmer culture though, they have always been quite spot on when talking of maintaining their godly blood. Cleansings would fit right into their mindset.
But yes, the Thalmor aren't as strong as everyone believes, yes they are strong but they have been slowly burying their own grave lately.
If they were strong enough to defeat the Empire, they would have done it. But they weren't and they aren't now either. They demanded the Empire to ban the worship of Talos because they already knew such a thing would cause a rebellion somewhere. They were pretty bold in the Great War as they outright opened a 5-year bloodshed; they had the power to do so then. Now they are basically dividing and conquering, which is a dead giveaway they don't have enough power to go on an open war.
Problem is, they made the Empire walk into a shadow of fear; the Empire is basically too afraid to do anything, as they believe the Dominion can crush them. So, even 30 years after the Great War, the Empire is still in ruins, unable to even take down a minor rebellion (such as the Forsworn who took over Markarth and the early years of the Stormcloak rebellion). They lost Hammerfell and Skyrim (even if the imperial forces win the civil war there, pretty much all the nord warriors who would normally join the Empire in the war to come, will be dead as almost all of them turned rebels), so that leaves Empire with a very small amount of forces and that's exactly what the Dominion wants.
For me, the Empire died with the Septims, so I don't really care what happens to it. Never been a huge fan of empires anyway. They can all die fighting the Thalmor for all I care. That would probably weaken the Thalmor further and then we nords could have the chance to swoop back in and crush them much easier. With both the Empire and the Thalmor gone, we could just form a new Empire featuring Skyrim, Cyrodiil and the Summerset Isles. Damn, Ulfric could become the new Talos if he'd play his cards correctly.
Iron Church? That reminds of Swole Acceptance with their Iron Temple and their gods: Brodin All-Spotter, Broseidon, and a few more I can't remember.
I dont think the dominion are strong or as strong as they were pre great war, but I do think they are powerful enough to finish the empire, due to the rebelion in skyrim and the scaring of the empire (empire still seems a bit "patchy" even after 30 years). Then again the dominion are still struggling to control Hammerfell which is showing weakness, but like the empire, there main forces might be readying for an attack at the border to cyrodiil