Nathan Fillion told Deadline that Book will indeed be recast if the animated series goes forward:
Absolutely, that’s the plan. Yeah, we’re bringing back Shepherd Book for certain. Ron Glass, unfortunately, is not available. Ron once joked that he didn’t get a part when they were looking for a Ron Glass-type, and here we are again. We’re looking for a Ron Glass-type, and it’s not going to be Ron Glass.
Fillion explained why none of the original writers, such as Tim Minear, aren't returning:
Running a show is an entirely different beast from recording a voice for a show. So there’s the original folks, like Tim Minear, who are running other TV shows. They don’t have a whole lot of time, and I don’t know that I could even afford them. This is not a big money-making venture, doing an animated program. But what we did manage to do is find incredibly talented people who also love Firefly. Tara and Marc met and connected over their love of Firefly. So when we were looking for showrunners, their passion was palpable for the show. We wanted to find someone who loved it and would care for it the way we do.
Fillion said he has no interest in exploring the post-
Serenity era:
You can’t bring back Firefly without bringing back all of Firefly. We toyed with the idea of spending some time in the show after the events of Serenity, and I honestly have no interest. I think Serenity was our wonderful farewell to what was an incredible opportunity. Had we only had one more chance to do something, that was it, and it was beautiful. I can’t compete with that. But what I can do is go back in time, bring the gang back together, and give people what they want, which is more Firefly. After Serenity, it’s not the same. I didn’t want to do this without my buddy Alan. And you know that’s a reason why animation is key, because Ron Glass is no longer with us. I like to think, in my heart of hearts, that this is something that he would have wanted.
