Interesting question. Here is my take on it:
I see a value to both situations. On one hand, you would have another console that would butt heads, directly, once again with Sony and Microsoft. If Nintendo would have come up with a "GC 2" and had it been comparable but cheaper than the other consoles, that would be a winner in my eyes.
With this new radical direction, and supposed low price, it will be interesting to see if it becomes a "primary" console or a "secondary" one. The games that Nintendo will publish will be good (I would have said fantastic a few years ago but some GC games let me down, hard), that isn't a question. What 3rd parties have in store is yet to be seen. If they are unable to port games, dev houses will have to make a choice, find a way to fit the controller controls in, not port, make an add-on device the controller (expensive for gamers), or split dev teams for entirly new games. I only see a few of those options happening.
I do like the controller idea, I can't wait to get my hands on it but for now, I remain skeptical until I see the games. We can dream of all the possiblilties but if they never get made our dreams will fall flat. Show me the games!