Soundwave on 16 May 2014
The DS actually has a higher attach rate than the 3DS at the similar point in their life cycles by the way.
Going back and looking at Nintendo's software shipments:
After 13 quarters, the 3DS has shipped 43.33 million hardware units with 162.9 units of software for an attach rate of 3.76.
After 13 quarters, the DS had shipped 64.8 million hardware units with 330.88 units of software for an attach rate of 5.1.
So the OP's point even on the basis of attach rate has been debunked. Attach rate tends to follow a bell curve, because at the tail end of a life cycle (especially for one as long as the DS) you get a lot of cheapo/budget parents who buy their kid the system with like 1 game that brings the attach rate down.
