The character was killed off in an early issue of the original Walking Dead comic, but will appear in the second season of AMC's adaptation.
"It's hard thinking about killing any character," Kirkman said in an official AMC interview. "If they're good characters, there are always more scenes to write, but this is the nature of things: There are zombies around. People gots to die."
The writer added that it would not be "an easy decision" to kill off Shane.
"He's past his expiration date by comic book standards, but Shane is by no means rotten," quipped Kirkman. "I think he's remaining fresh for a while."
Kirkman also revealed that the second season of The Walking Dead could differ dramatically from the original comics, due to Shane's prolonged life.
"While we're mapping out this arc and figuring out this story, we'll pull something in from the comic and then we'll go, 'OK, so how does Shane existing change this?'," he explained.
"It's really neat for me to treat The Walking Dead TV show as an alternate dimension where Shane lived, and there's all this different stuff happening because of that."
The Walking Dead star Jon Bernthal previously admitted that he is still concerned about his future with the show.
"We don't have to follow everything that's happened in the comic but this is the kind of show where people get picked off all the time," he suggested. "It adds to the atmosphere on set [because] we never know if each script is going to be our last."
The Walking Dead will return to AMC in the US and FX in the UK in late 2011.
> Jon Bernthal chats 'The Walking Dead'