Here, from Twitter, is Nintendo’s announcement.
Since you guys asked so nicely, here’s a release date for Pikmin 3: August 4. pic.twitter.com/h6ceglAiCB
The link leads to the picture you see on the side of this post.
Those crafty jerks! I assume they announced it after the Direct presentation as they wanted space for the news. Otherwise, Pikmin 3‘s launch date would have come amidst a flurry of reports on A Link to the Past‘s next game and the Virtual Console release of EarthBound.