It really depends if Timmins can fully recover or not. With that being said, the amount of research, methods, and technology the health system has now compared to even 5 years ago is astronomic. I have a family member that works at a concussion clinic that specializes in sport-related injuries and recovery. 5 years ago it was more or less sitting in a dark room and hope you recover, now it's actively visiting an OT clinic to help the recovery process goes smoothly and catch signs of any issues.
I have faith Timmins can fully recover. Do I think he has top pairing potential? Not really, but I can see him still turning into a very solid #3-6 defenseman.