Shutting down is a much bigger challenge; the worse I could think of is the idea of bitcoin losing its credibility due to manipulation.
No such information provided that killing BTC is possible.
And I really doubt btc can lose credibility over market manipulation, many people already know the reason why market is been manipulated, whales do this to create panic and weak hands will sell their coins away cheaply, this has nothing to do with btc reputation,
And as for government, they can only try to ban and that is as far as it goes, even when they ban trading still go on in the background, government can really do much because people will always find alternatives.