I think people are jumping a bit to conclusions here. I don't think anyone is saying the Dovakhiin HAS to be a Nord, rather Bethesda seem to nudge you towards choosing the Dovakhiin to be a Nord. Just as if the game was set in Black Marsh, Bethesda would probably nudge you into being an Argonian for the main quest.
But if one took the trailers too seriously, they'd also be pushing you to be a Nord warrior (who's gimped and specced in heavy and light armor. Heh).
I'm playing a Nord now, but a mage.. and it's still fitting. I could easily say having Esbern as my mentor "nudges" me to being a Nord mage. I could say that Dragon Priest masks quests nudge me that way too.
Or I could just take a completely different path, and say that nudges me. There's a representative of almost every character type in the plot, so it doesn't make you feel too out of place. You can be a Bosmer hunter, and not stick out. Because they're all over the place as well. You're only seeing Nord centrism if you want to.