Arya is never going to see any of her family again. We're just going to have to accept it. My #1-most-looked-forward-to-scene of the series was Cat and Arya finally getting to see each other again.
Also I don't quite think ratings will tank after the Red Wedding. People said they were going to stop watching after Ned died, but the first season finale had the strongest ratings of all. People will come back to see what the f*** happens next.
I DO think they could potentially tank a bit later, but that's for different reasons I can't say here. (I actually typed them all up, too, but then I remembered I wasn't in the Book Spoilers topic on the Cable & Satellite Board.)