For the people who think Nintendo would produce a system which was only as powerful as the XBox 360 or PS3 ...
The performance level of the XBox 360 and PS3 is really awkward in that they can do many advanced things (graphical, ai, physics) that define this generation, but they tend to struggle to do them and it is difficult to do many of these things at the same time; in contrast the Wii is in a different position in that it can only (really) do the things that defined the previous generation but you can do most of them at the same time, at a high quality, without really impacting game performance.
To put this another way, most PS3 or XBox 360 games have a few things that are impressive for the generation like advanced shaders, a large open world, or really good physics/ai but almost no games have all these things at the same time and maintain a HD resolution at a decent framerate. In contrast to this the (best) Wii games tend to do everything that was impressive in the previous generation (bump mapping, multi-texturing, partical/lighting effects) at a high level at the same time.
If the next Nintendo system was put in the same position in comparison to this generation as the Wii was (compared to the previous generation) it would be much more powerful than the PS3/XBox 360. The best way I can think of explaining this difference is, the difference in performance would be similar to the difference between the Dreamcast and the Wii.
