This actually depends on a lot of factors that we would not truly know until it actually happened. What time of year? (Summer/Winter) What time? (Day/Night) Where would you be when it actually happened? (ideal location already or on a trip/out of town situation) We all want to assume we would be "in the know" or in the "perfect spot to react" to the "Breaking News" of the SHTF, but the truth is more than likely you (& I) are not going to be in the perfect situation as the SHTF.
As for those claiming Power, Police, Fire Departments, Military, 75% still holding their job and being able to trade goods (in the short term)........ Your SHTF & mine are way off!
Bonus: Not being able to play an X-BOX or use twitter is NOT a calamity... NOT doing those will more than likely help you without a calamity anyway.....just saying