I don't think TES will be accused of copying if they have sentient, talking dragons. Even shapeshifting ones. I've read a few books that incorporate those.
Well, TES lore definitely includes sentient, talking dragons. So they've already copied (Tolkien, at least
) and what's done is done. Might as well run with it, rather than strip them out and pretend it never happened. And WOW isn't exactly original, having also copied the idea of talking dragons D.
TES lore also includes elves (copied), centaurs (copied), minotaurs (copied), mages (copied)... In fact, if you took out of Skyrim all the parts of TES lore that have been copied (sorry, 'inspired') from somewhere else, you wouldn't have much left
.
I think sentient, talking dragons are just fine. It's a good idea, never mind where it came from and who had it first.