http://www.gamefaqs.com/console/gamecube/
Not a single Nintendo game on that list. Japan doesn't even HAVE any games that are being released soon. Mostly what's being released now and those that are in development are 3rd party titles.
This is going to be the same deal as what we saw when the GBA was released. Game Boy Color and Game Boy games were backwards compatible with the GBA. What happened? They were phased out when 3rd party developers stopped making games for the others. The same will happen here. Nintendo's only GameCube titles they have intentions of releasing are Super Paper Mario and Twilight Princess. Nothing else is scheduled.
As someone who's been around when tons of systems were phased out, I can honestly say I know what I'm talking about. When the Dreamcast was released and Saturn was phased out, did stores keep the Saturn games in while Dreamcast was still there? No. When PlayStation was finally put to rest, did retailers continue to sell the games? No. What about Dreamcast, Nintendo 64, Game Boy Color? Did either of those stick around when newer guys showed up? No.
Stores will do whatever they can to clear out inventory. Otherwise, it's gonna sit there and they won't have room for the new stuff. Why else do you think GBA and GCN racks have gotten smaller?
And in case you didn't notice, not everything goes the way Nintendo wants. They wanted the GBA and DS to go along side eachother. What happened? DS eventually overshadowed the GBA and everyone, including developers jumped ship for the DS.
Btw, folks. Online retailers aren't very reliable either. Many of them carry the games no one wanted. They also tend to carry used titles, as well as overpricing certain titles just because they're no longer in print.
You find me an online retailer that'll sell me the Dreamcast games I want, unused and at an affordable price, and I'll show you a store that has every GameCube game in stock.