Nintendo has more Wii U games in development but they haven’t announced them yet. Presumably one of them is the new Zelda game, but Iwata revealed at an investor’s meeting that they did this on purpose so that to not give their competitors an advantage.
He revealed that he didn’t want to leave a long gap between announcement of new game types because it would lessen the impact or allow competitors to copy. I assume he is talking about Sony and Microsoft as competitors and honestly that’s really silly because, I doubt those companies care about what Nintendo do.
However, he did mention some new game types to be announced and the reason they aren’t announcing new games is that they want to keep a small gap. I guess that’s a fair explanation minus the competitor’s copying part of course.
Source – Nintendo.