There's so much sadness in this story: Nicole Yvette Brown has announced that she will not be joining the show on Yahoo! in order to take care of her ailing father. That's just heartbreaking on every level.
Brown to TV Guide:
My dad needs daily care and he needs me. The idea of being away 16 hours a day for five months, I couldn't do it. It was a difficult decision for me to make, but I had to choose my dad.
... [Dan Harmon] has been so wonderful about it all. He told me, 'Yvette, I'm praying for your dad.'
... I'm still Community's biggest fan and I'll still live Tweet episodes. It's very bittersweet. I can take care of my dad but won't be with my TV family. I don't want the fans to worry; it's going to be fine. Greendale is the heart of the show, not any particular character. Even if characters come and go, the heart of Greendale remains.
Brown also said she's left on good terms and is open to making a guest appearance, it's just that being a regular on a single-camera show is not possible for her current circumstances. As for how Shirley's absence will be explained, Brown added:
I am totally open to whatever Dan decides. I'm glad it won't be hard for them to explain where she is. She has three kids, a degree and a business. There are a lot of ways to explain her [departure].
As for Harmon and his fellow executive producer Chris McKenna, they issued a statement saying:
Yvette was an integral part of Community and is irreplaceable. We are sad to see her go and wish her the very best.
The resurrected show has now lost both Brown and Jonathan Banks (Buzz Hickey), and is casting two new characters to make up the lack. The first is a female consultant hired to help Greendale shape up and the other is a retired salesman looking to reinvent himself.