GWTW,
Another "When S* Hits the Fan" strategy, other than your island house with a garden strategy, is to be mobile.
With not too much money, it is still possible, with a valid passport from North America/Europe, to travel and live most anywhere in the world should or when "it" hits.
Years ago, I met a guy in Nepal who was doing just that. With only a small knapsack and an umbrella, he rented or bought anything else he needed.
You and you children may want to combine your island house with a nomadic strategy...especially if pirates haul ashore.
Me, we're off to Patagonia or Thailand should there be the need . They have (Argentina) Malbec in Chaing Mai...Maybe that's why Mark Faber lives there.
Cheers,
Baires