Pikmin 4 is "Very Close to Completion"
Nintendo's Shigeru Miyamoto has confirmed that Pikmin 4 is currently under development and is "very close to completion", according to an interview with Eurogamer taken earlier in the year.
Miyamoto said, "It's actually very close to completion. Pikmin teams are always working on the next one." Then, more recently, Nintendo confirmed the existence of the game in an exclusive statement: "We can confirm that Pikmin 4 is in development but that is all we can confirm at present."
It has not been confirmed which device Pikmin 4 will launch on but, considering the title is almost complete, we should expect a Wii U release.