It wouldn't affect me personally but it would cause me to sigh at the passing of a video game era. In that hypothetical scenario, it would be saddening to see a truly great company that introduced many Americans to the idea of gaming in 1985 have to sell themselves into the service of their hated enemies. I tend to think that the 3DS and its copyright would keep that from happening.
I wouldn't mind as long as I still could play their games. Who knows? Maybe the quality of their games would actually benefit from it because they wouldn't have to worry about hardware anymore?
But I don't think this is gonna happen. The 3DS is a success and if they step up their game with the successor to the Wii U in a couple of years they will be fine.
Even if they were to drop home consoles they would continue to make handhelds because that is what they are best at right now.
Personally, I just ordered a Wii U today. I don't care about third parties, but I expect BigN to step up their game with first party titles now. That is why I think the Wii U is so interesting right now, Nintendo first party games always have a level of polish that the other developers simply can't reach.
It would mean Nintendo can't take chances with hardware development since they're not the ones in control of the hardware anymore. At best they'd be making custom peripherals (it's easy to imagine the Wii Remote + sensor bar as USB devices).
Sure, some games might work best on a specific console, as a lot of Nintendo games make strong use of their systems' unique features. But hell, I would not be disappointed to see a Metroid game on Steam or something like that!