I don't think bitcoins are an economy by itself. If you say economy it is something that is produced and consumed by the people.
In bitcoins there is only a medium of exchange, nothing else. There is no economy to speak of here. The only thing bitcoins would
be in an economy is a way to pay for stuff, but it can't produce stuff, nothing goes around.
I agree with your opinion. Bitcoin is a medium of exchanges, an advance way of sending payments and storage of assets. It is not anymore economy but new way that our economy adapts. I believe that bitcoin helps our economy to develop and to become more advance in the near future. However, there are struggling times before bitcoin reach its stability and maintain the economic success of the world.