Metroid is on the back burner all the time because it sells like dogshit. Even the best selling (Prime series) sold a fraction of what Mario, Zelda, or even games like Splatoon do. Same for F-zero and whatever other under represented Nintendo franchise you can name. They are a business after all.
Still, Retro hasn't released a game in 3 years (Donkey Kong Tropical Freeze, great game), so I imagine they are working on a new 3D Metroid.
Still, Retro hasn't released a game in 3 years (Donkey Kong Tropical Freeze, great game), so I imagine they are working on a new 3D Metroid.