If they were to make Tamriel to scale, then to be realistically sized with it's environments, it would need to be at least about the size of Australia or so, and have hundreds of cities with tens to hundreds of thousands of buildings each.
Does that sound plausible for TES 6/7 to you?
It would be, in a word, AMAZING!!! But no, I can't see that happening. It would be too much for any existing system (pc or console) to handle. At least, for most systems, anyway. It would be a dream come true if they could make a game with all of Tamriel involved, even if it wasn't made to scale as the OP wants....