I guess you need to compare to the number of people who have a bank account and a credit card. Since BTC is easier to get than those 2, it has a huge future?
Bitcoin is different than a bank account because you need ID to get a bank account and at the moment you dont to get btc although that may change with regulations.
Credit card is easy to get with a good credit rating, they throw them at you but they also throw the charges to use it at you.
IMO bitcoin is waiting for that 'killer ap' to just explod in usage.
There was a good article in Times magazine talking about how many of the chinese public use Alibaba, if they started accepting it they may help a bit, depending on how they handle the income of btc.
This 'killer app' idea is not that bad! I thought about it a little and I hate to say it could be done and definitely can happen. But I am worried about
something. This killer app have to be some kind of ultimate bitcoin wallet. The one and only program you need to pay for everything, receive and send
bitcoins, it should be integrated with some of the leading bitcoin services like bitpay for example. But integrating it with services means that it also can be
compromised as well... And that is my fear.