Michonne is a complicated character who hides her emotions well but she has strong emotions. And a hard core drive to survive no matter what. After the attack on the prison when Hershel was murdered by The Governor she almost lost her will to live but she came back from that and went on to find love and family again. She would be the perfect choice to lead a spinoff.
Right now she’s firmly ensconced in the group and at Rick’s side. But a spinoff based on her life during and after the fall until she found Andrea would be a great premise for spinoff. But she could also carry a spinoff that takes place after All Out War and after some of the events in the main Walking Dead show.
Losing Carl is definitely going to hit her hard. At some point she will lose Rick too. And after that happens a show about how she goes on to survive after the loss of yet another son and partner would be great to see.
It’s always possible that she will die before Rick, but it remains to be seen how Rick will handle the loss of Carl. Carl’s been his motivation for everything since the very beginning. So it isn’t too hard to imagine that Michonne will be the last one standing of the Grimes family and have to rebuild her life again.