I think Nintendo is saying that they are really going to bring it on with the next console. That doesn't mean that they are going to drop support for the GC soon--as a matter of fact, if they are going to try to get their system out at the same time or before the other consoles, making sure that the GameCube ends with a bang is paramount.
The problem I see with all the hardware developers in their strategies for the next generation is this idea that if they get to the end of the rainbow first, then they will automatically get the pot of gold. If Sega's situation has taught anything, it's that getting a system out earlier than everyone else will not guarentee you success. The launch itself has to be perfected with good games out of the gate, hardware that isn't falling apart all over the place, and the perception that your system has excellent support. The other component is hype. Sony could sell a piece of crap console and still garner the majority of marketshare because Microsoft and Nintendo have not convinced PS2 owners that they should jump ship. One key to making that happen is hyping the ability of your system, even if you're using theoretical numbers (I still see people defend their system of choice with those theoretical figures).
The other key to making that happen is having a good showing in THIS generation. Cutting their losses and putting all their resources into the next Nintendo system may save them money in the short term, but if they are serious about dishing out some tough competition, it would only be smart to continue with strong support the console now and starting to convince people with other consoles that Nintendo is the one they need (with some top tier developers warming back up to Nintendo while Nintendo's own departments work on some high profile sequels and secret projects, I think we are beginning to see Nintendo work towards that goal). The last three or four years have shown with brutal clarity that a reputation and name recognition can and will be more important than timing. People will wait for a console if excited enough (unfortunately for Sega,the brief period when the Dreamcast and PS2 competed demonstrated this all too well).