Andreas is totally right about this kind of attack, it would be terribly expensive, and it would fail very quickly. It is not easy (if at all possible), to destroy Bitcoin, and I think something like this would be the last option in some possible attempt to destroy Bitcoin.
It's going to be very expensive to do it, and the community will always be in consensus to kick out bad actors that are threat to Bitcoin's existence.
However, given the fact that China has more than 50% of the hash power, I see a big problem in that fact. We all can see that China makes strange decisions when it comes to Bitcoin, and one day they can just decide that all mining farms become the property of the CP.
Will China decide to be a bad actor , or a good actor?
Of course, it will not destroy Bitcoin, but the panic that would then prevail would have a devastating effect on price.
That's a market problem, not the network's problem. The market will always sort itself out.
I also think that Bitcoin is no threat at this time and that no state plans to destroy it, but they turned more to the control and supervision of those who use it.
They would leave it alone, if it wasn't a threat.
