Her? Mae* Whitman, the actress that played Ann Hog on Arrested Development, told Hollywood.com that she will 100% be in the fourth season.
"I definitely, definitely wouldn't ever let this chance go by without being a part of it. I told Mitch [Hurwitz] that I would stand outside the sound stage until he would let me just walk through the background or something… I would say yes, you can definitely expect to find a little bit of Ann hiding in the background somewhere, at least."
Plant would be really good at hiding in the background.
*It's interesting that her name is the same as the character that George Michael really loved. [...]