Right now each and everything is connected with internet and technology. The future of banking might happen through blockchain technology and bitcoin in mass adoption. By that time what will happen with the banking process if there happens a termination of internet connectivity for few days time.
I wouldn't have been able to imagine life without the internet in this era. Internet is so important, it is an obvious need, a part of life .. On the general aspect, the internet shutdown is not impossible, it is not inviolable. But it seems too serious for all activities related from personal online needs, commerce, economics, ... lack of internet? it's too serious to be dreadful.
“If we hold the cell phone in our hand, we would rarely talk to a stranger on the bus. The world will not be destroyed if it loses the Internet for a few days, ”said Stine Lomborg at the University of Copenhagen
Anyway, it's just an assumption. People will have many alternative, compatible inventions if that happens!