A higher money velocity => lower BTC/USD, but yes, the current price implies a huge future growth of the bitcoin economy. This is what sam is saying and I agree. I happen to think that we will not see that growth/adoption, but that is a different question.
There's no obvious reason why BTC velocity should go lower than USD velocity. If anything, its electronic nature and potential for fast settlement times should indicate a much higher velocity than USD M2.
EDIT: Sorry I meant to say the velocity will decrease.