The nintendo DS was such a success, and it did not have fast hardware.
Even if it's a little expensive and not fast, being able to run free games and software would really be an awesome feature. People say there's no money in it, but hardware is fast and cheap today, so any slow device would be cheap to make.
The raspberry pi is really awesome, but I don't understand why they're not making the final step of releasing a full device. Of course there are many projects out there, but they're not produced in high quantities, meaning not cheap, not well marketed, not always well designed, and often require non-trivial additional tweaking.