Nvidia likely doesn't see it that way. They survived in an industry that pushed out half of the competitors every generation, and slashing prices was typical in the death throes. They are the last GPU company standing, with ATI moving into the second tier with the other embedded GPU companies (e.g. on ARM).
Nvidia certainly hasn't suffered from not being in the other consoles.
It appears they are pursuing a strategy of making consoles irrelevant rather than fighting to be a low-margin design supplier for a business that may be in decline.
(Actually I think the console makers are just barely in time with their refresh. Switching to a x86+GPU platform is admitting special hardware no longer has an advantage. Or, to put it another way, the magic is all in the GPU and you can match or (with $$) better that in a regular PC. But most consumers haven't internalized that and they still have a shot at getting most users to refresh their hardware and remain locked into the platform for another generation. Waiting another year would be a disaster. Even Christmas 2013 is a long way off when it come to gamer's opinions.)
making gaming irrelevant with a toy shield that plays Android games?
Quit that stroking dude... Nvidia will fast become irrelevant.. they are being squeezed from the low end by Intel haswell graphics and a price war with AMD on the high end.
Nvidia wasn't in 2 of the 3 major game consoles of the last 7 years and their GPU segment certainly didn't seem to get hurt by it. I think you may be overestimating the volume of future sales if you think Nvidia losing the PS4 is going to put them in serious trouble in a couple of Q's