People use "NextGen" a lot to define the "power" of a console, but frankly it's only meaningful to define gaming generations as the gaming machines which were released during the same time and competed with each other.
The Dreamcast, PS2, Gamecube, and XBOX are all considered to be part of the 6th generation, despite the XBOX being technically superior. While the Wii is considered in the same generation as the PS3 and XBOX 360 despite being technically inferior. The "inferior" PS2 and WII are generally considered to be the best-selling machines of their generation despite their relative technical inferiority. It's not about power; it's about competing for the consumer's wallet and mindshare, retail space, and how to spend development resources and marketing.
Now I'm not against using "NextGen" to be an abstract descriptor of being technically advanced, but people need to know the damn difference between the two definitions and not mix then up!
While the WiiU might not be as powerful as the "PS4"/"Durango" (we'll have to see if that's even going to be true); when retailers, analysts, journalists, developers, and publishers speak about the upcoming/next generation, they're definitely not talking about "power". So why do these "power" arguments constantly keep popping up in these kinds of threads?