5 years isn't so bad, I'm guessing (I haven't actually checked) that the Wii has turned a profit by now (or will soon), so it's not as if it'd be a poor financial decision for the big N.
I can't decide whether I want long or shorter lifespan on the Wii.
On one hand, the next console would probably be Wii HD which comes with everything built in (so I don't have to buy motionplus).
But then the other side is, I spent money on the Wii and have only owned 7 games for it (including Wii sports, I'm sure you can guess what the 7 are)