It is probably true that governments would have a hard time killing BTC by going after transactions and, harder yet, the network due to its decentralization. What if they just decide to cut it off its food supply?

What if the banks decide that their profits may be at stake? What if the banks of the major countries decide to launch a coordinated attack and close all accounts of BTC exchanges. How then would new money come in to BTC and how would existing BTC holders get money out? Who would want to accept BTC at that point? Could the banks even do this without a legal reason?

Concerned...