Hasquarl on 19 March 2013
Just to add to what Cheebee is saying, I found this in Nintendo's original Press Release for the DS announcement:
"Nintendo DS will be marketed separately from the company's existing Nintendo Game Boy® Advance portable system and Nintendo GameCube™ home console."
Link: http://www.g4tv.com/thefeed/blog/post/703412/read-the-original-nintendo-ds-press-release-when-ds-was-a-code-name/
They probably wanted to have the GBA running for a few years with the DS, but when the DS went sales crazy, they just dropped the GBA altogether.
