If he says he doesn't know. Then that pretty much says that he's probably not coming back. If someone has plans to comeback and they are going to make every effort to doing so, then they state it whether they feel it or not at this time and make dates for the future. When he says that and refers to sports psychology, it basically means he's mentally done or he just doesn't have the belief or confidence to do it anymore.
Hope you find that fishing hole and retirement location you are looking for.