Hmmm, that's interesting. I read the article that talked about some of the Gamecube surprises planned, and then when I came back to the thread I saw "LINK" and immediately I wondered if MK would try to do what SCII did and include a Nintendo character in the game. I doubt it would be Link, just because that has been done before and it seems a bit too obvious, but it seems possible that they would add a new character for the GC version, not necessarily Nintendo, but just some reason to buy the game for GC instead of online functionality.
All in all I'm very pleased they're not only releasing MK for the GC but they're even trying to make up for the lack of online. Take notice third party's everywhere, this is how it should be.