Coffee with Games says, "Going back to that "rumor" now. In videogamer.com's article, an employee from a large publisher was quoted as saying, "Just heard a rumour that you may be interested in: Nintendo are going to announce a new platform at GDC. Some devs have already started work on it."(emphasis added)
If some developers are already working on Nintendo's next system, perhaps it's High Voltage Software, and The Grinder will be their debut game on the system."