“Miyazaki has decided that “Kaze Tachinu” (The Wind Rises) will be his last film, and he will now retire,” Hoshino, who heads Studio Ghibli with Miyazaki, said.
Hoshino did not give any further details, saying only that Miyazaki will be holding a briefing in Tokyo next week. ...
How about, he's been at it a long time, he's had a string of hit films (many iconic) and he's 72 years old.
You get worn out after a while. And it gets to be time to do other things, because most of your years are now in the rearview mirror and you have to use the ones left to you wisely and well.