I'm puzzled about this oversaturation of 2D platformers.
Let's see--we saw DKC, right? That's one. We've got NSMBU. That's two. Yoshi Yarn isn't coming until 2014 at the earliest and my guess is we won't see it until 2015. What else has Nintendo shown that is a 2D platformer?
As for the people wanting Retro to be "unleashed," you do realize most of the people behind Metroid Prime are gone, right?