If every country really started cracking down, sure bitcoins would be put into a choke hold VUT that's not going to happen because so many cou tries fully support it. Even if bitcoins where a japan only currency, they would still hold huge value. Keep them no matter what happens in your county.
It is up to the user that how the person use to do if the person is having the large amount and he is willing to invest it for the profit the he will be able to get the income and the money till it get high and the people who are now showing the interest will force the government not to stop the bitcoin and to let the bitcoin get more and more wide. So I think the government will not stop the bitcoin for sure.