As is every transition period between gens is that there is one maybe two years of games coming out on the other system until it eventually dies out.
Me personally I have a gamecube and ps2, and I hate the ps2. To the core. Gamecube has great graphics and great games that I grew up with. i.e. Mario, Zelda, Metroid, Fire Emblem,Starfox, etc. Heck, I even slightly enjoy that Animal Crossing game. And on the next gen, the brilliance of Nintendo shines with a new way to play games. To tell you the truth, this past gen, there were not that many appealing games out there to me. Except for the aforementioned games. Nintendo's stragedy is playing out really well. Most likely it will be many gamers "Second system", and many developers are jumping on to system more than they ever did the GC. Many people that I talk to that are not Nintendo people, say that they are interested in playing FPS with the controller.
What do PS3 and XBOX360 have? Better Graphics and a hole in your wallet that you won't soon repay.
It will be cheap to develope for, which will give many developers a chance to make games for it, and you won't be paying 60 dollars per game either. Remember it is gameplay that matters, and graphics will only go so far.
That is my two cents and long live the Revolution.