I actually think Aaron Cruden + Piri Weepu negates the need for Dan Carter, because Cruden can make the ball go places and break the line, whilst Weepu can be relied on to kick and score at goal.
That IMO is a pretty stupid thought, missing the best player in the world (ever) doesn't get negated by an average flyhalf and a good scrumhalf. Cruden doesn't have half of the ability that DC has at anything.