In 2005, various print and online publications released news of Metroid Dread, a new 2D Metroid game in development by Nintendo for DS. Nintendo has always been cagey about the game, and since then the game has been inconsistently reported as being cancelled or indefinitely delayed.
However, scanning an unassuming control console in the second half of Metroid Prime 3 yields the following message: "Experiment status report update. Metroid project 'Dread' is nearing the final stages of completion." Whether this means the game is indeed close to release is unclear, but it suggests Nintendo may not yet have shelved it completely.
Shacknews has sent requests to Nintendo regarding the matter.