Usually hard to say, but I voted for after next year's E3. If they haven't given us anything to go off of other than "It won't be MM3D yet" and "It might relate to A Link to the Past" at this point, they're probably still very early in development (if real development has started at all) and it will thus take more time for them to have anything to show us. I predict we'll get something substantial between E3 of 2013 and 2014, no later than the E3 of the latter year. Nintendo is probably focusing more on Zelda Wii U, since it's sparked the most curiosity and the 3DS technically already has a Zelda game for it in the form of Ocarina of Time 3D.