Every. Single. Time. since then this has been true in my anecdotal experience. Sometimes I've really regretted mentioning it because I've mentioned it to coworkers sort of casually and then, sure enough, their parent was dead within 6 months of the break.
After the first few came true I said it more seriously like, "Listen, you need to prepare for their death..."
The only appropriate thing to see say to a co-worker in that situation is a polite "I'm so sorry to hear about that, I hope your mom feels better soon." Keep the prepare for death conversations for close friends and family. Even if in was a close friend you happened to work with, the workplace is not an appropriate place for such a conversation.
If you do not wish to discuss it with coworkers, some of whom may or may not be friends, it's your choice to raise them or not. Focusing the attention on important matters could be done tactfully, which is very different from not talking about things.
If it's by fiat, there is an ulterior motive of "think happy thoughts, preferably shallow". There are such workspaces. There are also those that keep grave silence by fiat or unspoken convention.
But he died shortly afterward.