I live just a few hours away from the Yellowstone caldera. I don't really have any long term survival plans in case of such an event
I can, however, envision one or two alternate SHTF scenarios. An economic collapse that could easily run faster than anyone might imagine. Such a scenario may cause government disruptions regarding social benefit programs (read welfare, etc.). Recipients of such in this day and age will not react civilly when the checks stop coming (cards stop working). And the average Joe American will not be a happy camper if the government finds it necessary to freeze the banking system in an effort to stop or slow the financial tidal wave. When the trucks stop running America will grow hungry fast. Hunger trumps even sex in terms of primordial response.
A severe power disruption in one or more major population areas caused by enemies of the state. Such disruptions might well expand to rural regions in terms of power re-allocation to stabilize (or attempt to stabilize) the major centers. Rolling blackouts, allocated internet access, etc. will set America's teeth on edge. Food rations would not be far behind.
Infectious disease is always something to respect in a world where international travel is so prevalent and air travel has become a common mode of employment transportation. As good as our preventative system appears to John Q. Citizen, a vicious retrovirus could raise holy hell in the highly populated and mobile centers of every continent. Even once identified and administrated, such a virus would leave a population so frightened the subsequent social consequences would be severe.
If Yellowstone blows I'm gonna really be pissed... for a few minutes anyway