Fake Alt (Bit-)Coin Attack
If there is the possibility of effectively turning the bitcoin network off then I think one attack to consider that I haven’t heard about is to create a new network and attempt to grow enough available hash power that could sustain such an attack. Here the distinction is the social aspect of the coup.
This attack might not seem plausible given the lead of bitcoin’s hashrate, however, even if that were so it should still be considered in theory.
But an attacker preparing such an attack would not be necessarily directly and actively implementing available hashrate but rather garnering support for a future social movement to do so (which would include private and government agreements and infrastructure agreements)