They pretty much have to make Negan the lead now
With Andrew Lincoln leaving Michonne was the obvious character to fill his shoes, but now that shes leaving Negan/Jeffery Dean Morgan really is the biggest star they got left. They really aint got much choice but to make him a full on good guy and have him be the lead on the show. Daryl isn't the type to be the leader and focus of the show, he's a great side guy but his character just aint the right fit for the Rick role.
Negan could easily slide into the Rick role and give the big speeches and be a strong leader, they've already started his redemption this last episode. He tried going back to Sanctuary and picking up where he left off, but he saw its empty and his empire has crumbled, he has nowhere to go except back to Alexandria.
Also you can tell he truly cares about Judith and wants to be better for her. I can see the whisperers attacking Alexandria and Michonne lets Negan out to help and he proves himself. Cause i don't see Negan going back to just sit in his cell again for years. He's gonna earn his redemption and eventually become apart of the community just like in Carl's dream.