Some people say that the network signal is not good when you are away from home. If there are currencies that are traded offline, that would be great, and maybe there will be large-scale application scenarios for digital currencies! What do you think?
People would always find a way to manipulate the balance or fake the coins when transactions happen without confirmation from a reliable source. People would be double spending the same coins when they don't require online confirmation.
But again it doesn't mean the internet is the only way to confirm it. Some satellite technologies like BeiDou that sends and receives signals from device without internet can one day be used as a way of confirming transactions. But that would be a huge upfront investment and most probably centralized. And again as always people would keep trying to hack it's security to manipulate the transactions.