If all goes to hell in a handbasket, I would want something over which I had direct control, not something like non-US equities.
Physical metals I can understand, but not gold mining stocks.
As far as shorting goes, what does that get you? More money? If money becomes essentially worthless, what good is that, unless you have a mountain of it?
Speaking of which, how much would represent "a mountain" in the event of collapse? By that, I mean how much would you need to have in order to still be wealthy after the crash?
I think a diversified farm is a good investment, no matter what commodity prices currently are, as long as they haven't driven up land prices too high. For anything to be worthwhile, you need to be able to trade as well as produce, and for food, there is always a local market, making trade less expensive than if you had to use an established long-distance distribution system.
And as far as that goes, I think only really good, reliable, defensible distribution systems would be a good bet. Know of any? Pipelines vs rail vs trucking vs shipping?
Just thinking out loud.