PoW Consensus Change To Combat Attack

G'day Bitcoiners. My question is about a 51% attack. I understand the disincentives when it comes to bad actors looking to make a profit, this is convincing to me that it makes no sense and would be ridiculously financially damaging to any entity that attempted this. However...

I'm interested in the US or China attacking the network with a 51% attack, where their interest is to destroy bitcoin, not make a profit or gain any lasting control - and I'm focusing specifically about the proposed solution where a change of consensus protocol (from SHA256 to something else for instance) would be made to make the attackers ASICs worthless.

Wouldn't this destroy the hashing power securing the network by wiping out everyone elses ASICs as well, and make the Bitcoin network vulnerable to much cheaper attacks following the initial attack that results in us implementing the consensus change?

So an attack from US would be them burning billions of dollars to 51% attack the network, then we change consensus and they would attack a second time but utilising the new consensus, having to spend only a fraction, and then a third time, and a fourth time etc. Do we have an answer to this kind of attack? Thanks in advance and GFY.