But what would happen if one state (you know which one) could actualy gain control over more than 51% hash rate though?
You mean the Chinese government? The majority hashrate is already located in China:
https://www.coindesk.com/highest-in-2-years-65-of-bitcoin-hash-power-is-in-china-report-findsWe're still talking about private companies running these mining operations, not the government. The confiscation of private mining facilities to launch a 51% attack seems rather unlikely as China knows better than to kill their own cash cows.
Well depends what their intentions are, they might confiscate all the farms to launch the attack and destroy btc to be able to force on public their own "cryptocurrency". In this way, they would have the best of both worlds, the biggest competitor would be gone, and everyone in china would have no other choice but to use their centralized government shitcoin. It's actually scary what countries as powerful as china can do to bitcoin.