On GDAX the trade volume for BTC/USD is now about $1.4 billion per day. And there are other exchanges too. So yes the market could fulfill that trade. Would probably bring the BTC price down but it wouldn't be catastrophic.
Given the completely unregulated nature of these exchanges, that 1.4 billion USD could be legit, it could be wash trades, it could be inhouse bots doing crazy things to rig the market. , or it could just be a complete fabrication.
