It is more likely that Central bank will one day issue digital currency of their own, based on the fact that metal coins are expensive to manufacture (often costing more than their face value).
How about the bitcoin mining then? Are the electricity and anything that be needed in mining more expensive than bitcoin itself?
Bitcoin is a threat to them for sure but I don't think they have to be worried yet as it's going to take quite some time before bitcoin starts to eat into their profits but I hope its sooner rather than later. I think people are always going to need banks though but bitcoin will likely flourish in parts of the world where people do not have access to a bank.
Yes it is a blessing for those who don't have bank accounts, it would surely attract them towards bitcoins, and as of today we even don't need credit cards for online purchases as bitcoin is taking care of that too, so it would surely affect the business of banks.
Actually I think bitcoin will be more difficult to understand for people who dont have bank accounts, since they would think that they dont really need it. I guess most of bitcoin users here are people who have bank accounts, and feel that the banks are suck with their high fees.