And the Wii was tracking way above the PS2 for quite some time, just sayin'.

True, but the Wii was bought by quite a few new gamers, true casuals.  And quite a few of those mainly bought it after playing Wii Sports at a friend's or family member's house.  Maybe they bought a game or two after that.  One or two games can not hold interest in your console forever.  People just lost interest in the console.  The PS4's situation is MUCH better, since core gamers are buying it.  This means it should have great legs, just like any PS (home) console.

The core audience is indeed more stable but do we know how long the PS4 will sell, what its peak sales year will be etc? Much is uncertain at this point, it has been only a year and early trends are not always indicative of end results.