Could a 65 year old man with emphysema regain some stamina and sing well again, or is it too late?

Emphysema: It depends on the severity of disease. A pulmonary function test judges severity. Proper inhaler therapy would go a long way to help as well. Avoidance of smoking would also be of great assistance in helping emphysema patients. Finally, i strongly believe in pulmonary rehab. This program works with pulmonary patients to improve ability to exercise. Better pulm. Function may assist with singing.

Absolutely!: 65 is young! a diagnosis of emphysema is not a death sentence. People with emphysema live full, good lives. The most important thing is to not smoke, get proper treatment, regular follow up with your doctor, and rehabilitation if needed. No reason you can't sing with emphysema.