Iwata always talks about the need to remain humble and pay attention to the customer. He's been rolling with Nintendo through good times and lean times before, so I think he knows that getting complacent means getting dethroned.
So no, I don't think Nintendo is going to fall prey to the same hubris that market leaders have manifested in the past.
"The worst part about these reviews is they are [subjective]--and their scores often depend on how drunk you got the media at a Street Fighter event." — Mona Hamilton, Capcom Senior VP of Marketing
*Image indefinitely borrowed from BrainBoxLtd without his consent.