Actually, objectively, isn't the Wii on par or actually ahead of the GC in terms of hardcore game delivery, first-party and third-party combined?
Eternal Darkness, Wave Race, James Bond, Sonic Adventure 2, Smash, Pikmin, Extreme G, Rogue Squadron, Luigi's Mansion and a couple more games maybe...
versus
Zelda, Excite Truck, Super Paper Mario, RE4: Wii, Godfather, Scarface, Elebits, Sonic SOTR, Trauma Center, and definitely a slew of other games, from FPS' to sports titles to Warioware.
I certainly understand that the future isn't as set in stone as some wish it to be, but the past speaks for itself... so far we haven't seen any shift away from hardcore game titles, just an increase in the alternatives being offered.