Durring one interview, Miyamoto mentioned that he believed the Gamecube's hardware was good enough for it to be a viable system for 8 years ... He was probably correct and the only reason we don't see many new Gamecube games is that its sales were not good enough for it to be a viable system for 8 years.
Claiming long lifespans is marketing-speak to reasure people to buy into your system; it is not a sign of vision or of a long-term plan because it never comes from the people who's long term plans matter (Third party publishers).