Seriously, I can't believe people are about to set themselves up for disappointment AGAIN. There's plenty of evidence that the graphics aren't going to get any better:
1. We've seen some graphics, and they weren't that much of an improvement.
2. Developers have agreed that estimates of 2-3 times as much power are about right. In fact some said 1.5-2 times.
3. Nintendo has stated time and time again that it wants the system to be cheap to develop for - a big part of that is not requiring ever-increasing armies of artists.
Personally, I think the graphics already look better than the GameCube (in most cases). I'd be happy if they improve even more, but I think it would be really optimistic to expect the remaining improvement to be as big as the improvement we've already seen.