Let's take a step back. This is The Walking Dead, where looks are deceiving, and planted evidence can clue us into future reveals. Earlier in the episode, Carol, bound and under guard, exchanged words with one of her captors, a grisled chain-smoker with a tendency to talk too much, who let a significant clue slip: "We're all Negan." A sudden fit of smoker's cough prevented any further clarification.
This fits with the story told by the escapee who cops to being Negan. Rick asks him whether Negan was inside the compound or was one of the survivors offed by Carol and Maggie. "Both," says the hostage. Negan may be nothing more than a spooky sobriquet, adopted by the Saviors to frighten the innocents they terrorize. Or maybe Negan's a leader so diligent about protecting his own mystique that he orders his followers to fake the title and keep others guessing.
In any case, there's a good chance the man (or men) responsible for tormenting the Hilltop remains at large -- very much alive and, when he hears of how many casualties the Saviors have suffered of late, very inclined toward vengeance.