Depending on your relationship with your boss, you may be able to ask him how you can step up to the plate and be more helpful. However, he may not take your offer graciously. Do you think he would take that question as an affront?
It is critical for every business to have a succession plan in place. An 80-year-old business owner who does not have a succession plan in place is unrealistic.
However, it may not serve you well to be the voice of reality--the one who asks the boss what his plans are for ensuring that the company will move through a future transition.
Is there someone else better suited to do this touchy task?