It's hard to believe if internet connection got terminated since almost people in this world using internet for chat, business, online shopping, work from home, gambling, etc.
But if it will happen, Bitcoin can't be traded and the price could be dropped significantly since there's no volume and activity about the transaction occur.
By that time what will happen with the banking process if there happens a termination of internet connectivity for few days time.
What about using SMS to process the transaction? just like this thread
Offline cryptocurrency transfer?