If you google “ferfal”, you will find lots of information on how Argentina fared during a financial collapse about 10 years ago. He runs a blog and has written a book or maybe two about his personal experiences and observations.
Specifically to the question of electrical power, his blog states that it sometimes became sporadic with rolling blackouts, significant voltage drops and brownouts, but did not disappear completely. He purchased a device that protects his home from low voltage conditions that could damage his appliances.
His opinion concerning power loss in the U.S. and other first world countries was that in an economic collapse like Argentina experienced, we might face similar rolling blackouts and brownouts, but total loss of power would be unlikely.