Discussing consoles and their unique features, Nintendo president Satoru Iwata suggested that non-3D games maybe in the pipeline.
Iwata commented that software shouldn't have to take advantage of every unique aspect of a system, and in the case of the 3DS, there are a fair few features to choose from. 3D output, StreetPass, SpotPass, voice input amongst others, and Iwata feels that even 3D itself could be an optional feature.
Nintendo may choose to develop a title that focuses more on motion play (as we know motion together with 3D has its issues), or a more social/StreetPass nature perhaps. Maybe a stronger focus on pure visual detail.
The company previously noted that there wouldn't be 3DS games that don't do 3D.
I think there could be a Nintendo 3DS software title which does not use the 3D feature at all, and I believe Nintendo will develop such software. Instead, other features of the Nintendo 3DS should be focused on. It might be a communication feature, or other functions (such as the gyro sensor or the motion sensor). The important thing is that each respective software title has its own characteristics, and appeals to the consumers in a way that fits the software.
All of the announced first party games for the 3DS do focus on 3D output as standard, however - including Kid Icarus: Uprising, Super Mario 3D Land and Mario Kart 7.
Would you be satisfied with 3D-less games on the 3DS? Should all 3DS games output in 3D? Perhaps a cheaper "2D" version?