I seriously doubt the Dominion would be in the shape to invade anyone for many years, unless they have a Numidium Mark 2 hidden away and ready to go! Likely they never had that many soldiers to start with (which is why they only tried to invade Hammerfell and even then only after the Empire had had most of it's forces wiped out in a failed invasion of Akavir), and since Elves have a low fertility rate, combined with the fact that they booster their numbers of soldiers with a large number of female soldiers (potential mothers) means that when the Empire and Hammerfell both wiped out huge numbers of Dominion troops, that it will take perhaps two, three or even four generations to replace them. Basically, the only part of the Dominion that counts as far as supplying soldiers (since Valenwood is likely still restless after the Thalmor Pograms of Bosmer, and Khajiit, while excellent warriors, make poor soldiers) is the Summerset Isles, which is a fairly small landmass when compared to Cyrendiil or even Skyrim.
Firstly, while they did fight the Empire to a standstill, the Thalmor themselves must have been severely weakened themselves - after their defeat (and yes, they technically did lose that war) they were even driven out of Hammerfell, and never tried to re-invade.
