Gravity the Ghost on Twitter has made some pretty compelling points and has probably provided one of the best (and only) logical theory about the rumoured Nintendo Direct.
He believes that Nintendo is just going to drop a Nintendo Direct with either little proper announcement or none at all. His two reasons for this are in the form of both of Nintendo’s tweets. Firstly, the flaming Chibi Robo tweet from @NintendoAmerica is linked to the fact that this game was announced one one of two Nintendo Directs that went live without an announcement.
The other, which was on the @NintendoNYC Twitter was a tweet from a Mii in a Hotdog suit from Tomodatchi Life, the other Nintendo Direct which went live without an announcement.