To me SHTF means a localized break-down of services.
Ice Storms in New England 2 years ago resulted in wide-spread loss of power for an extended period of time (5-10 days) For the first several days many stores in my area were without power, some streets were impassible. Still, most basic services remained operational. Water, Sewer, Gas, police, fire, etc remained mostly operational. It was bady and favored the prepared, but it was not SHTF.
In New England, the most likely events that would result in the S truly Hitting the Fan are major natural disasters (wide spread flooding from a few years back certainly bordered on this in some area where water, power, sewer and gas became unavailable for a week or longer in some places. Or financial break-down.
The later is the one that truely scares me today. The projected budget for 2011 showns 1.6 trillion dollars in borrowing on 2.1 trillion dollars in income with some 800 billion dollars in debt service (payments on debt) and that 800 billion dollars is based on the US having one of the most favorable interest rates in the world. Add to that the fact that many of the states and towns are projecting major budget shortfalls and they are unable to run on debt like the federal government.
There comes a point where these governments need to begin cutting into basic services or raise taxes, either of which can start the spiral that can result in the total break-down of services, and the S hits the fan.
Other senerios that could result in a local break-down of services include: A local outbreak of a dangerous and highly infectious disease that results in a local or regional quarentine to prevent further spread. A terrorist attack on one or more basic services. (New England is more succeptible to this than most like to admit, but I wont share how)
Being prepared for the SHTF possibility total loss of services (Fire, Police, Government, Water, Sewer, Power, Oil/Gas, Financial, etc) to me encompasses preparedness for the lessor, more likely minor emergencies.
Home catched on fire, floods or otherwise becomes unlivable
Jobloss
Extended / Serious Illness and or injury.
Loss of one or two major services for an extended period of time (like losing power for 8 days 2 years ago)