i think the DS will have a fighting chance in the spring with the arrival of the PSP. Sony has a reputation of creating hardware that doesnt last when it takes punishment, so enless they change that, sony is going to have problems.
and there are all the classic games that they can release for the ds that are favorites of all of ours. Golden Eye, Mario 64 (which im hooked on playing right now) as well as Animal Crossing.
So there is going to be a battle with the hand-helds between sony and nintendo, just like there has been with the other systems that they have put out.