Why it would make sense: Carl’s a badass. Simply no question. But he’s still a kid and killing him is to kill someone who, on paper at least, might not be as valuable as the adults from which Negan has to choose. Also, what a great way for Negan to exact revenge on Rick for orchestrating the mass murder of the Saviors. An eye for an eye, if you will. (Too soon?)
Why it wouldn’t make sense: Negan’s last words before swinging the bat: Anybody moves, anybody says anything, cut the boy’s other eye out and feed it to his father and then we’ll start again. You can breathe, you can blink, you can cry. Hell you’re all going to be doing that. Plus, if he killed Carl, he’d lose Rick altogether. LOCO. And that probably wouldn’t be good, as surely Negan sees the value in Rick.
Final take: Carl lives to see another season.