(gonna be honest, most of this is about stuff that wont even happen until season 7 and beyond if at all, but the seed for these hypothetical events have been planted this season)
Was reading some reviews for last nights episode and came across this comment
"Maybe they are setting up for a villain that is going to do something really bad and due to Morgan and or Rick, they will jail instead of kill the villain."
Got me to thinking.
In the comic, at the end of All Out War, Rick, instead of killing Negan, does exactly what I mentioned above.
Now this is thinking REALLY, REALLY far ahead and the show might not even last this long, among other factors BUT
What if throughout this season, and maybe even into the next, we have Morgan trying to chip away at Rick's new "take no shit from anyone" outlook, try to bring him around to his way of thinking. Or at least find a middle ground.
Assuming the show does cover All Out War and remains fairly faithful to it, it would explain why Rick would spare Negan, and in a more satisfactory manner than the comic handled it I'd say.
Jumping ahead even further to the Whisperers Arc where we've had readers speculating that Rick might turn to Negan for advice or help, I think it could be interesting, assuming Rick and Morgan are still alive/the show is still on at this point, for Negan and Morgan to play the Devil and Angel on Rick's shoulders.