That DS redesign concept in the Disgaea DS ad sure is nice, isn't it? But is it real? Who knows. We have our doubts. Redesigning the exterior of a DS is an "easy" thing, but adding widescreen would create a 16:9/4:3 gulf in DS gaming that we just can't see Nintendo going for. As for the official word, Nintendo are saying it's "purely rumour and speculation". Which, hey, we knew already.
Nintendo dismisses widescreen DS claims [Eurogamer]