With my parents, I'll typically just change the subject... sometimes by asking about one of the dozens of elderly and sick in the congregation.
There's been a very few times that they've pushed my buttons enough for me to push buttons back, then I'll remind them that I'm old, unmarried, childless, and have nothing saved for my fast-approaching retirement age because I'd been told how close the end was back in the 1970s, 80s, 90s, 00s, and now the 2010s. And I'll remind them that none of their parents ever expected to die (but they did).
If my siblings are around, I'll use some sarcasm like, "Yep, that's why we call these the Last Days... because they last, and last, and last, and last!"