Ds disrupted not only game market but lots of others. If youre familiar with the popularity of pocket dictionaries andtranslators in japan they go for several thousand dollars. A ds translator software went for 300$.
Now, in ds they had graphically inferior gaming and really casual games like puzzles etc. Even thefeel of ds games feels somewhat limited. With 3ds, suddenly they arecapable of running a psp like monster hunter. It wont look as nice as a vita monster hunter, but for many it will be goodenough. This forces sony to try and outdo ninty by having better graphics but for most, the graphics isnt the issue, its for example, 3d.
Moving downstream would be like sony moving to match the lower grade games