Well Jim did you ever read Dark4kn1ghts thread?
It was a hot topic about a member that was leaving society and heading to the high regions of the himalayas and then deep into cave systems with
himself and 3 other married couples all professionals.
This was based on his wife's best friends fathers death bed confession where he claimed to know of an event that would meet the criteria of what you
have suggested in your OP.
The problem was that he was shredded by the debunkers and for the most part ignored and discredited by the majority.
I think that hints should be made for those that have the eyes to see and ears to hear. That would be about 10% of the population.
"You can lead a horse to water", as you know and for the most part people like to live in the fantasy world of what they choose to see as reality
rather than the truth that is available in abundance in a myriad of ways.
I have considered your question many times and in short have to say that I for one believe that this is already the case and unfortunately the only
people I can see surviving will be the same people that have always survived to perpetuate this 0 society and the evil that it wallows in.
Now fess up what do you know and how to survive it!
Peace, and excellent question my friend...