On the other hand, if it ceased to exist, not long. It is generally assumed that power would stop to be provided in less than two months. Probably much less. The problem being that most of the infrastructure is not automatized enough, end-to-end, to ensure a complete support for a long time. A lot of manual interventions are required.
Perhaps things will get better when we'll have robotic cars and trucks, and automatic production, expedition, transport, delivery and refilling of stocks.
But I don't see how commercial corporations would be motivated to ensure a fully automatic production system, given that assuming the disappearance of humanity is assuming the disappearance of paying customers (at least, in the current situation).