Just returned from a shiva visit to friends. He lost his mother. He lost his father a few months ago. She lost her father about a year ago. That's about two years of caring for sick parents and the change tthat comes about with their loss.
This isn't the first couple I know that lost more than one parent in the space of a short time. Friends of mine in Beit Shemesh lost two (three?) parents in the space of a month or two. And a couple in my shul in Jerusalem lost three parents over the course of as many weeks a few years ago.
In at least one case, one of the young children of one of these parents asked if any of her other grandparents were going to be dying soon.
At least I have a few weddings and bar mitzvahs to look forward to (too bad three of them are on the same evening).