Definition of market cap:
Market capitalization (or market cap) is the total value of the issued shares of a publicly traded company; it is equal to the share price times the number of shares outstanding. As outstanding stock is bought and sold in public markets, capitalization could be used as a proxy for the public opinion of a company's net worth and is a determining factor in some forms of stock valuation.
But to define what are the bitcoins actually worth we would have to assume a lot of things. Check how many bitcoins are up for sale and you find something like 6800@bitstamp+8400@bitfines+350btce+100itbit+65@campbx = 15715BTC
So if I go in and sell 15715BTC, I could basically create a flashcrash on US markets. It would take even less to crash EU or China markets. The fiat money I would get from selling this would be around 8 million USD.
So no I have sold 15715BTC and got 8 million USD. The market maybe crashed faster by people jouinng me in the selling, or people would send in fiat en masse to buy up cheap bitcoins.
So can we really say how much are the bitcoins worth right now? I say no. We can speculate about how much fiat would be up for grabs if an early adopter starts to sell off.