It wasn't worth it. By comparison, Richard Pryor, the funniest stand-up of our generation, is suffering a chronic illness that prevents him from performing. On one level that's sad and depressing, but it's also good to know we'll always remember him at his peak, instead of as a washed up hack doing inane commercials for long distance service. People handle deterioration differently. By contrast Janet Reno, displaying the same symptoms, comes across like a scared, cornered Pekinese.
Some people seem immune to deterioration.
Aretha Franklin was recently featured on a TV special which included a clip of her singing opera, filling in for Pavarotti. She sounded operatic for about three notes, then hit a note that was pure Aretha. Most artists don't know when to quit and dilute their legacy by putting out miserable, inferior stuff in their last few years. Schulz has avoided this fate. So let's rejoice that his legacy is intact, wish him as much pleasure and as little pain as possible in the time he has left, and send him a fond farewell.