Even if you don't know him by name, if you have a passing familiarity with Japanese anime, you've probably seen a Hayao Miyazaki film. Miyazaki is one of the founders of the famous Japanese anime production company Studio Ghibli, whose logo is from one of the films Miyazaki directed, My Neighbor Totoro. Miyazaki first retired in 1997 after directing Princess Mononoke (after which he directed some of his most recognized work in Spirited Away and Howl's Moving Castle), and again in 2013 after his work on The Wind Rises.
Well, you can't keep a good serial retirer (and legendary animator/director) down and Miayzaki will once again return from retirement for another feature film. To be clear, Miayazki did not step away from creative things altogether in his (latest) retirement doing things such as illustrating a samurai manga. There was also word of him coming out of retirement back in November 2016 to create an animated feature film from what was originally supposed to be a short for the Ghibli Museum: Kemushi no Boro (Boro the Caterpillar).
Though it wasn't explicitly stated that Boro would be his next feature film, it does seem to be official that Miyazaki is out of retirement and working on his next feature film, as stated by fellow Ghibli founder Toshio Suzuki:
Toshio Suzuki confirms at the Academy that Miyazaki is definitely un-retired. And Suzuki is producing his next feature.— Cartoon Brew (@cartoonbrew) February 24, 2017
BREAKING: Studio Ghibli producer Toshio Suzuki confirms that Hayao Miyazaki is currently working on his next feature length film— Chuck D. (@WolfgangChuckD) February 24, 2017
Studio Ghibli's Hayao Miyazaki, Toshio Suzuki, and Isao Takahata
If it is Boro, it was reported that Miyazaki wanted to have the movie out before the 2020 Olympics, likely in 2019.
Welcome back Miyazaki!