This is largely baseless.
For example, the Xbox 360 is typically lauded as a console for hardcore gamers. Games on this console are typically selling significantly better than they did on the Xbox, despite currently having a lower install base. Halo 3 will end up significantly higher than Halo 2, CoD 4 and Assassin's Creed have been huge, Oblivion did fantastic early in the system's life, Mass Effect will sell well over 2m when all is said and done. The list goes on and on.
There has undoubtedly been a huge increase in the success of casual games, most of this is attributed to the success of the DS. On the Wii most of the truly successful games have been more traditional, with SMG, SMBB and Mario Kart leading the way. Even on the Wii, traditional games are not dying - although casual games are certainly playing a larger role in that consoles success.
Ultimately this just seems like another attempt to discount GTA IV's success.
