Theoretically, she could die (they could all die), but I don’t think she will so I say to you:
TPTB will lose viewership if Michonne dies, plain and simple; they are
looking for shock value and striving to be more brutal, but the television industry is still an
industry and what does industry do? Put out the products that will have
them reap the most success. Having Michonne on their show makes it an
interesting and dynamic show. She is an iconic, widely popular character in her own
right. She, Rick and Daryl are on most of TWD merch and AMC is running a
business; you do not get rid of your ‘best sellers’ for shock value.
Especially when half of the other characters aren’t as interesting or as iconic as Michonne is.
Also, since Richonne happened, I think she is safe. Michonne is Rick’s long term love interest now like comic book Andrea, as so stated by Scotty G. Andrea and Rick have been together for the longest time, it will be the case with Michonne (who has taken that part of Andrea’s storyline).
Canon Richonne was in the works for three seasons, SG had plans for them to be together before he was even the show runner. He would not do all of that planning, give Rick and Michonne this wonderful build-up and finally pair them together just to kill one of them off. So I say they are both safe at the moment.