Since the Gamboy started Nintendos handheld empire they have been able to hide a lot behind those profits.
Do we know for sure N64 and GC was not sold at loss? There are reports that the Wii was supply constrained for the first couple of years due to the console was sold at a loss http://mynintendonews.com/2014/05/31/nintendo-apparently-supply-constrained-the-wii-as-was-losing-money-on-each-unit-sold/ .