I sincerely hope it goes dormant for a while so it doesn't turn into a beaten dead horse franchise like Mario, Zelda, and Pokemon. The two things keeping Metroid from joining the other major franchises in being over-beaten dead horses is the fact that it's the only one of these series with a solid ever-expanding storyline, and has had more variation from game-to-game than anything seen in the others (except maybe for Mario). Face it folks, every Zelda game is the same old story over and over and over again, replete with the same old gameplay, puzzles, pacing, set-up, and plot twists. There's a reason I hold Majora's Mask and Link's Awakening in such high regard--they were the different titles.
After a long hiatus, I would like to see Metroid returned to Retro so that they may continue the franchise, chronologically, after Fusion and maybe delve into some serious history on the Chozo--or the origins of Ridley. Though, to be honest, I'm getting tired of seeing Ridley in every single game. The "Prime" series can't continue since it was officially closed.
