The length of time a person has owned a console will affect how much software they have bought!
Therefore, attach rate increase with time, at least over the first few years of the cycle.
Really, all the amazement over Wii vs. 360 software sales comes down to that. People have been concluding all sorts of crazy stuff about the generation based on Wii vs. 360 software, first amazed by 360 software sales, now amazed by Wii software sales. All the while forgetting that attach rate is a function of time, not install base size.
360 may maintain a higher attach rate for the next 3 years, even as Wii starts to sell many, many times more software. It shouldn't surprise anyone, or be seen as a cause for concern for Nintendo. Wii is younger than 360, d'oh.
"[Our former customers] are unable to find software which they WANT to play."
"The way to solve this problem lies in how to communicate what kind of games [they CAN play]."
Satoru Iwata, Nintendo President. Only slightly paraphrased.
