The best I can think of with $150 is:
-A GPU twice as strong as the Wii U.
^That's not gonna cut it unless it has some massively killer apps, and even then 30million at most. Then again maybe that's all they need.
For a portable centric platform that's pretty beastly. I think that would be more like $200. Double the Wii U in terms of GPU and it could handle some PS4/XB1 games on the go. Sure some of the effects may have to be scaled back and the resolution may have to be 960x540, but still. Knowing Nintendo it'll probably be less than that.