Yeah, I agree it can be jarring even when it's plausible, and can quickly make your work age very poorly if you guess wrong about the legacy of the thing you're referencing. The 2040s and 2050s are, alarmingly, not that far away!

I guess my assumption is that the longer Rowling goes on and the more unhinged she becomes, the more likely it will be that people will at least have heard something. She's starting to dabble in Holocaust denial now, so I'm afraid we may be very far from the bottom of the depths she can sink to and the full impact on her public image and her work's legacy.