Let me clarify my thoughts on this a bit.
If we see a Wii+ or WiiHD (something in Huelen's GREEN band) in 2010, I think that will be the end of standard console cycles from Nintendo, at least until Nintendo falls back into the position they were with the Gamecube. Nintendo could make continuous iterations of PPC+ATI GPU+Bluetooth every 2-4 years and maintain compatibility, libraries, and momentum for a long time to come. I think if they took this model, they'd be making a refinement on the PS1->PS2 strategy, and that Microsoft would follow suit. The only player that seems like they might be unlikely to do so would be Sony, but only because of the challenges presented in maintaining backwards compatibility with the PS3, while at the same time making a system more palatable to developers. I think if Nintendo took this strategy and was successful with it, I think Sony would make a less exotic PS4 (xenon-like cpu, shared memory pool between cpu and gpu) and fall into the pattern from there.
It's a business model change that makes sense
.
I could see a progression in names too.
Wii (2006)
WiiHD (2010) (HDMI Port - HD Twin Speeds - More memory - bigger flash -
- Controller refinements)
WiiHD Plus (2013) (more and faster - more solid framerates at higher resolutions. Controller refinements)
WiiHD Plus Turbo (2016) (same)
WiiHD Plus Double-Turbo (2020) (same)