Nintendo Wii could sell for over 15 years.

[Erik Aston]

The reason that Wii could last a lot longer than any previous console is that there will be no Wii 2.

SNES offered a souped-up version of the NES experience. PS2 offered a souped-up version of the PS1 experience. Etc.

NES and PS1 were the standard-bearers of a certain type of experience, and they transfered their momentum to their successors; not their imitators. (PS2 did not because of PS3 overshooting the market and Wii disrupting.) As winning consoles, NES, PS1 and PS2 all had 10-year lifecycles.

But when a console like Game Boy wasn't replaced for an extended period of time, and remained the standard-bearer for a certain type of experience, it lasted well over 10 years, still crushing souped-up imitators into the late 90s.

Unless they simply abandon their current strategy, Nintendo are not going to replace Wii with a souped-up version of the Wii experience. Whenever their next console comes out, it will be because they have a lot of ideas, representing a new type of experience, that they can't offer on Wii. If Sony or MS tried to offer a souped-up Wii with their next console, it would chase away their established PS3/360 audiences, and not give them any power to fight Wii (just like Gamecube and XBox were both outsold by PS1 during last gen... Look it up). So Wii will be able to remain the standard-bearer for the Wii experience basically forever, and be able to go as far as that experience is appealing to people.

Then we'll get to see how "evergreen" their evergreen titles really are. Nintendo themselves of course will always be supporting their latest console, so the long-tail sales of Wii will rely on third parties and the Nintendo catalogue.