This kind of doomsday speculation makes my head hurt, but I agree on some level with the “cash is king” sentiment. Even if TSHTF, physical cash, even though just paper, is still:
1) recognized by all
2) easily portable
3) virtually impossible to counterfeit
4) scarce
So yeah, I think physical dollars will still be useful as a medium of exchange, perhaps even more so than gold, if all hell breaks loose.
Paper dollars will just be one arrow in your quiver. You will also need long term food supplies, guns etc. Check out Ferfal’s blogspot, or his book “The Modern Survival Guide.”
Argentina went through a monetary collapse. It’s not just armchair survivalism and “fending off biker zombie attacks” in your fortified compound in Montana. It’s reality based. Check it out.