I obviously wouldn't word it like that 
She's not dying, she's in very good health actually, but she's almost 81. She's a grade 8 piano player and some of my favourite memories of her when we were kids was her playing the Teddy Bears Picnic for us on the piano, we loved it! Every time we went to her house we'd beg her to play it and she did, every time. I watched a video last night of an elderly gentleman playing the piano and it suddenly hit me that one day, I'll never again get to hear my lovely grandma playing piano 
She might have a good twenty years left but at 81, who knows? She has had a few falls at home, the last one only a couple of years ago and she broke her leg.
So would it be weird and morbid to ask her?