What are the chances of getting emphysema if the person did not smoke for 30 years?

Low but not zero: While tobacco is the leading cause of emphysema, its not the only. If you quite smoking for 30 years and have healthy lungs, they are likely to stay that way.

Depends: Some patients are more susceptible to damage from tobacco and develop emphysema even after quitting smoking for many years, and others never do. It is all very individual and cannot really be quantified.