Then again, it looks like Carl is all posted up in the sewers here, which is a different situation than what we see in the midseason finale. Maybe Rick and Michonne are going from one sewer part to another sewer part? (I know, it makes very little sense.) Maybe they try to escape and Negan is still hanging around?
Regardless of how it goes down, it seems we'll be wrapping up Carl's long journey with Rick and Michonne. Whatever Carl hasn't put down in those presumed letters from earlier, he has the chance to say here.