Bottom Line:
Next generation is the next cycle of consoles that compete with one another. The WiiU is more closely related in terms of power to the X360 and PS3, however it was just released to compete as one of the "Big 3" in the next cycle of consoles that will all be out in the next 1-2 years.
Consoles stop being referred to as "next-gen" usually a year or two into a consoles life, or even a year or two after the launch of all 3 competing consoles. (I use 3 as I am referring particularly to the 8th Generation.
Only after this generation is over, will anyone be able to look back and say whether a console was a success, so only then will anyone be able to dismiss the WiiU as not being a part of this generation (Sells nothing, Nintendo releases a new console) because then it did not compete at all. (The Wii DID compete with X360 and PS3. Don't debate it, because it's a damn fact that there was competition between them, both over the hardcore, and even more so over the casual market that Nintendo broke into)
