I'm sure a lot more people are familiar with the term Lou Gehrig's Disease than Amyotrophic lateral sclerosis. Anyway, wiki says, "Most people with ALS die from respiratory failure, usually within 3 to 5 years from the onset of symptoms. However, about 10 percent of those individuals with ALS survive for 10 or more years."
So obviously a small percentage of people can hang on for a while, but anybody with this disease is worth keeping a close eye on, which is all I really recommended in the first place. If his condition worsens this year, next year, or whenever, be ready. We may be able to see the end coming.