A sport like tennis the majority would quit competing when they reach their 40s. It's very physically demanding and you have to keep in top physical shape. Teaching or coaching young players can go on longer. Once in a while you hear on the news a retired senior in his/her 90s competing in a marathon.
Nobody in my family pursued a career in music. And nobody who took piano lessons as a child asked their parents for a piano. It's usually the parents who enrol the kids to music lessons as an extracurricular activity with no expectation anybody would become a concert pianist.
The lady in the article chose piano at a young age and made performing part of her life. A career is not meant to be permanent. Not having a good eyesight wouldn't be a serious problem as many pianists would perform pieces from memory. Having a bad hearing is more difficult to fix. Hearing aid don't always give good result when performing music. She would have to quit performing if she has signs of dementia. Playing as a hobby is something many people like myself would do every day than teaching or performing on stage which is at another level. The physical limitations to performing is already showing so it's time to quit. Instead of teaching, she can run a private music studio as a manager and hire teachers instead of doing any teaching herself. At the moment teaching is something she can still do and gives her a sense of satisfaction.