Lasereth, for one of your experience in the world of games, you should know better than to say Nintendo's fate rests upon the home console market
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The problem won't be a lack of support. The Cube has horrendous 3rd party support, but it's still a financial success, due in no small part to Nintendo's first and second party efforts. They have the advantage of a far larger development base than Sony or Microsoft, and an overall much higher quality in the end product. Quite a few share visual style, setting and characters, but if you think Mario Tennis is the same as Mario Strikers, you're missing the point.
They rely on the strength of the brand, not the strength of the sequels, to carry the torches. With the exception of Mario Party, Nintendo have almost no hand in direct sequels, at least, not in the same vein as most other developers. A good example is the N64 Zelda titles. Majora's Mask shared a game engine and main character with Ocarina of Time, and little else. Completely new setting, many new characters and more new game mechanics than you can shake a stick at. They certainly avoid any situation where you're forced to buy a sequel to finish the game properly (Halo 2, I'm looking at you...)
From what I've gathered, the difficulty with the Revolution won't lie with getting third parties on board. What remains to be seen is if Nintendo can market those types of games aimed at non-gamers successfully, while reminding the more mainstream gamers that there's still plenty of love left for them.