Indeed. Same VA so I think that accounts for the mistake, but Rikke was not at Helgen.
I'm reluctant to get into this debate over here, but no, that calculation is faulty. What's left of the empire at greater strength couldn't defeat the Dominion before, so what makes you think they will the 2nd time around? Rather, the empire won the military campaign and lost the political campaign, which I think highlights the fact that they no longer have their mythic grounding. This is TES after all, so geopolitical (nirnpolitical?) factors are less important than mythic ones. There are no dragonfires, the Alessian pact is over, and it shows. Now I think the locus of anti-Thalmor resistance is in the individual provinces who are resisting the Thalmor, in the "make way" of the redguard, the Nords' pride in their role as always returning Skyrim to their control, and potentially also in the survivor spirit of the Redoran, as well as the fact that the Thalmor themselves are usurpers and perverters of the Altmer way and will probably collapse from within as well as without.
I do think it likely that there will be a Dominion even after the Thalmor are booted out (by the Psijic if by no one else), and that the empire is on its way out no matter what the outcome of an individual playthrough in TESV. And, I welcome that change. Another Cyrodiilic empire reboot is the dullest outcome I can imagine.