Well, it really depends on what you define "Selling for over 15 years" to mean ...
I expect that Nintendo will look to release their next generation of hardware in 2011 or 2012 in the western world, and the Wii will slow down in sales from there (with measureable sales until 2015/2016). At the same time, the Wii hasn't (really) been launched in China or India and it is possible that Nintendo could sell the Wii there for quite a while, and only replace it with their next generation of console in 2016/2017 (with measureable sales until 2019/2020).
For most people this would mean that the Wii had a 7/8 year (because that is how long it was the most important console on the market for), but it could still be selling somewhere in the world 15 years after it was released,
