One console doing great does not mean another that's doing well is doomed. Besides, I think they are totally different markets. The DS is mostly for a younger crowed (I hear 70-80% are sold to kinds under the age of 16). The PSP is more adult oriented, with home brew, and movies.
Plus, there is nothing right now on the horizon that is better than the PSP at what it does. It still has a long life ahead of it.







