Below is a pretty graph I made showing attach rates based on Nintendo hardware and software shipment reports (and 3DS digital sales).
Please do note that the DS first released in Q3 FY2004, while the GBA and the 3DS both released in Q4.
Also, please note that the GBA had its successor release by Q15/16, depending on whether you count the Japan-only initial release. DS had its successor release on Q25.
As you can see, the 3DS attach rate is currently tracking only slightly above the GBA in terms of attach rate, but has already surpassed the attach rate of the GB. The new 3DS has most likely been the final hardware revision that will have a major impact on 3DS sales - and its attach rate, which may be noted by a slight flattening of the slope around Q17/18.
Nintendo stopped reporting GBA shipment figures after 32 quarters, and DS shipment figures after 39 quarters.
EDITL I will set up another thread on 29 October with updates and over-all figures for all Nintendo platforms starting with GCN and GBA, with final figures for N64 and GB. So, uh, please don't post here!
I personally predict an attach rate of 5.6 by the end of the 3DS lifespan.
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:3
