The katana-wielding Michonne is a fan favourite from the original Walking Dead comic, with recent rumors suggesting that True Blood's Rutina Wesley had been cast in the role.
"That's not confirmed," Kirkman told reporters at AMC's press tour event in Pasadena. "I can say that's definitely a character we want to work into the show at some point in the future. Whether that happens this season, I don't really know."
New showrunner Glen Mazzara added that Rick (Andrew Lincoln) and Shane (Jon Bernthal) will be at "the heart" of the latter half of the second season.
"Rick proved himself to be a leader [when] he put down Sophia," said Mazzara. "You have these two Alpha males sparring for position and we get a lot of great story out of that. And it puts everybody else in a difficult position on that farm."
The Walking Dead's Norman Reedus (Daryl Dixon) recently promised that the remainder of season two will be "more action-packed".
"In the second half, after this hiatus, people are done talking," he said. "It's all kind of firecrackers from here on out."
The Walking Dead will return to AMC in the US and FX in the UK in February.
> Frank Darabont reveals aborted Walking Dead premiere plans
Watch a preview for the return of The Walking Dead below: