To answer that part about the non-gamers, no they don't buy that many games, yes they are still playing wii sports.
Edit: Let me clarify how I know this before someone asks. There not buying more games because there still having fun with wii sports. Non-gamers are easily pleased from the same game for a long time. My sis still likes Brain Age. I forget I have it.
I'm sure what the hardcore crowd does is try to beat a game as fast as possible and when there done, it's on to the next big thing. Non-gamers don't play their games in long sittings and beat everything right away. Since they don't play that often, one game can satisfy them for a long time.