What if a 51% pool would censor all blocks that were not mined by that pool? It would boost the profitability of that pool tremendously and create strong incentives to join that pool.
Combine that with legislation and pressure on the exchanges and big economic nodes to play along...
Voila, you have a centralized state-controlled network.
I think you're ignoring the impact such an action would have on the stability of the Bitcoin market, and subsequently the price of Bitcoin. It would send the network into absolute chaos which would result in plummeting market prices as confidence dramatically dropped. The people with the most likely ability to do this are also the people who have the biggest interest in maintaining the stability of the blockchain, and the Bitcoin market.
When there are financial instruments that let you short the price, what is there to lose? On the contrary, if you are a superpower that is threatened by the decentralized network, it's a double win.
Yes there are miners that are long term invested into Bitcoin. But what would they do in such a scenario?
