Using your example of Sony, let me try to explain what I am thinking:
Most of you guys will remember the demise of Dreamcast. One of the reasons of its failure, was that Sony made sure that the not-yet-released-at-that-moment PS2 was always on the talk of gamers, to convince most of them to wait for it, instead of just moving from the PS1, Saturn or N64 to DC, as Sega was trying.
While it is not the same scenario now, the lack of hype from Nintendo for WiiU could be well used by Sony or MS to begin to build expectations for their new systems, making possible early adopters of WiiU (on the 'hardcore' niche) to wait for next PS or Xbox.