We're going to miss the Captain Rainbow videos. Nintendo isn't likely to release any more once the game is out in Japan (which is this week), unless one of two conditions is fulfilled: either it is announced (and then subsequently advertised) for other regions, or it becomes a massive success and Nintendo promotes it forever, like Wii Fit. It's a bit too quirky for evergreen, expanded-audience status. Enjoy the fourth, and possibly the last, Japanese Captain Rainbow commercial!
As for localization prospects, we want to believe, but we aren't really getting our hopes up for a game about old (non-Mario) Nintendo characters, given Nintendo of America's apparent disposition toward the Virtual Console.