What can stop Bitcoin now?
These won't stop bitcoin, but any one could definitely reverse Bitcoin's current direction:
- FinCEN going after exchanges for not filing as money transmitters (and/or for not registering as money service businesses) for selling "prepaid access". (This includes those exchanges serving customers in the U.S. regardless of where the exchange is located).
- Coinbase, BitMe, BitFloor, and CampBX being served subpoenas to cough up the USD and BTC transaction history for each of its customer accounts.
Another thing that could hurt bitcoin would be a tax on virtual currencies. For obvious reasons, central banks and corrupt governments would certainly favour the idea, and could use their political influence to try pass a new tax law using arguments of illegal activities such as money laundering, drug abuse, under-aged gambling, etc., being facilitated by bitcoin. That wouldn't kill bitcoin, though.