After buzz for quite some time wondering if it was going to happen, not to mention hints and references here and there, Nintendo announced in a Nintendo Direct today that Majora's Mask is going to be remade for the 3DS. It's going to ship in Spring 2015.
Iwata's said that they're trying to maintain the same level of challenge of the original game while making it accessible to everyone (whatever exactly that means). Other than that, we have no indications so far of what the game might be like outside of this trailer: