Opsec, a list is beyond my bandwidth at the moment, but in general:
anything that assumes the level of mobility that people have gotten used to (cars and gasoline)
anything imported from far away
anything that is "cutting edge technology", especially that requires a lot of sophisticated, delicate, high-maintenance infrastructure to supply. In particular, telecommunications and 24/7 power grid (I think power grid will stay up, just not 24/7/365)
Yeah, Offdalip, I hear the same kinds of misguided plans, and shake my head.
It's OK to assume bought supplies. It's not OK to assume that they are available all the time, at an affordable price. The transportation and communication networks will break down. Look at what happened to southern Louisiana and Alabama--not just New Orleans (which is the only part anybody seems to care about), but the whole area. Infrastructure in that part of the world never fully repaired--and perhaps never will be for at least the indefinite future.
Oh, something else I worry about: replacement parts for equipment!! Most of it is imported!! Not to mention that it's getting ever harder to find parts anyway, as globalized merchants keep switching suppliers!