Haven't seen the doc but I was listening to him on the radio last night and the guy sounds like he's trying to lay serious demons to rest in this fight. He was saying that he considers getting back in the ring as a victory in itself, like this is some form of therapy for him.
You can never really tell but it will be interesting to see how all that stuff manifests itself. Maybe he'll fight like a man possessed, but he was such a high intensity fighter that it's easy to see how he might struggle to reach those physical levels again. It's not like he's some technician who can fall back on his skill and his innate understanding of the craft should his body start to let him down.