Nobody here can say. It depends on his general health (what other medical issues he has), genetics, activity level, symptoms, and, to some extent, luck. If he can avoid getting hospitalized or having a serious fall, he could live another 10-20 years. PD doesn't generally kill people. It's not like Alzheimers or some of the Parkinsonisms. If he can avoid choking on food or falling and hitting his head, PD will probably not cause his death.

Thanks you, Ginny for your response. Understood!