As far as I remember, the caldera erupting is not an extinction level event (for humans at least)... would be bad for sure, but southern hemisphere would manage I think
No, nations do not have the means to feed their constituents in a nation ending disaster. It's easy to move food from Florida to California in a state sized crises, but the logistics of maintaining a just in case food supply for hundreds of millions distributed around the country? It's a safer bet to assume you'd die in the disaster than to convince people to plan for the future.
https://www.reddit.com/r/MapPorn/comments/1bvy6sz/by_popular...