Bruce Timm has been more or less in charge of DC's cartoons and animated movies since 1992, when Batman: The Animation Series first debuted, and it's no coincidence that DC cartoons have generally been uniformly awesome since then. But now Bruce Timm is stepping down from his role as supervising producer of DC animation to work on more personal projects.
Two things: 1) Having steered the best, most functional portion of DC entertainment for over 20 years, Timm has definitely put his time in, so we should just count ourselves lucky he stuck around so long; 2) he'll be replaced by James Tucker, who's got plenty of DC animation experience, having directed and/or produced Batman Beyond, Justice League, Batman: Brave and the Bold, Static Shock, and more. Also, Tucker has a very promising quote in an interview he gave to Voices from Krypton:
"I'd love to use more of a variety of characters, but that's something I don't have control over," [Tucker] says. "Granted, Dark Knight Returns was long overdue to be adapted and I'm glad they did it and did it superbly. But beyond that, I'm not really interested in replicating, image by image, word for word, something that was in a comic book, because you can’t replicate that experience or feeling. You’re basically getting a secondary experience, so you have to make it your own in order to make it work as a movie. Creating films in which people are going through it with a checklist saying, ‘Okay, they took that out, they took that out…' I’m not interested in doing anything like that."
That sounds great. Still, though... a Bruce Timm-less DC animated universe sounds like a pretty weird place to be.